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DAIRY TECHNOLOGY 

A TREATISE ON THE CITY MILK SUPPLY, MILK AS 

A FOOD, ICE CREAM MAKING, BY-PRODUCTS OF 

THE CREAMERY AND CHEESERY, FERMENTED 

MILKS, CONDENSED AND EVAPORATED 

MILKS, MILK POWDER, RENOVATED 

BUTTER, AND OLEOMARGARINE 



BY 

C. LARSEN, M. S. A. 

Professor of Dairy Husbandry, South Dakota State College, Brookings, 
South Dakota 

AND 

WM. WHITE, B. S. 

Federal Dairy Inspector, Manhattan, Kansas 



FIRST EDITION 
FIRST THOUSAND 



NEW YORK 

JOHN WILEY & SONS 

London: CHAPMAN & HALL, Limited 

1913 









Copyright, 1913, 

BY 
C. LARSEN AND \Vm. white 



Stanbqpc ipress 

F. H. GILSON COMPANY 
BOSTON, U.S.A. 



CCLA343073 



I / ^ 



PREFACE. 



The manufacture of butter and cheese has been carried 
on by man from time immemorial. But there are uses 
of milk and its products that are comparatively new. 
Modern man has invented and discovered many ways of 
increasing the commercial value of milk and its products 
by using them for a great variety of purposes. 

These uses for milk are here grouped together and treated 
under the one head — " Dairy Technology." This sub- 
ject treats of the production and preparation of sanitary, 
certified, modified, fermented, dried and condensed milks, 
the manufacture of ice cream, renovated butter, oleo- 
margarine, milk sugar, casein, etc. 

At the present time information on these subjects is 
widely scattered and somewhat indefinite. It is the pur- 
pose of this work to give experiences and results of work 
carried on by the authors; to secure from bulletins, papers, 
addresses, and other sources, reliable data dealing with 
these subjects; and to compile and arrange this material 
in such manner as to be a ready reference for the student 
of this phase of dairying. 

The authors reaHze that many of the subjects treated 
are in the midst of a transitional period. Future experi- 
ments are likely to add valuable information. The writers 
have endeavored to obtain the best possible present in- 
formation along the various lines discussed, and they hope 
to make changes and additions as rapidly as the authentic 
information can be secured. 



CONTENTS. 



PART I. 

MILK AS A FOOD. 
CHAPTER I. 

PAGE 

Milk — Its Properties and Composition i 

What is Milk ? i 

Properties of Milk i 

Composition of Milk 3 

CHAPTER 11. 

Normal Milk and Its Products as Food 5 

Palatability of Cows' Milk 7 

Digestibility of Milk 8 

Raw vs. Heated Milk 9 

Use of Milk with Other Foods 9 

Relative Cost of Milk lo 

Skim Milk H 

Buttermilk i7 V 

Cream i8 

Butter 19 

Cheddar Cheese 20 

Cottage Cheese 21 

CHAPTER III. 

Abnormal Milk 23 

Poisonous Milk 23 

Colored Milk 24 

Bitter Milk 24 

Stringy or Ropy Milk 24 

Colostrum 24 

General 25 

V 



VI CONTENTS 

PART II. 

CITY MILK SUPPLY. 
CHAPTER IV. 

PAGE 

Extent and Importance of this Industry 27 

Condition of City Milk Supply in Past Years 29 

Investigations in Illinois Cities 29 

Milk and Infant Mortality 30 

Epidemics Spread by Milk 32 

Sources of Milk Contamination 7,2 

Bovine Tuberculosis t,^ 

CHAPTER V. 

Improvement of the Milk Supply 35 

Inspection of Dairy Farms and of Milk 35 

Cost of Inspection 36 

The Score Card ^j 

Advantages of Score Card Inspection 41 

Results of Score Card Inspection 42 

Inspection of City Milk Plants 43 

Milk and Cream Contests 45 

Number of Inspections made in New York City 47 

Limitations of General Inspection 47 

Classes of Milk 48 

1. Certified 49 

2. Inspected 49 

3. Pasteurized 50 

4. Modified 51 

Results of the Improvement of Milk Supply 51 

Infants' Milk Depots in New York 52 

Milk Depots in Other Cities 53 

CHAPTER VI. 

Certified Milk 55 

Origin of the Term " Certified Milk " 55 

The First Medical Milk Commission 57 

Milk Commissions 57 

Requirements of the Milk Commission of New York City 57 

Details of the Workings of Various Commissions 64 



CONTENTS VU 

PAGE 

Use of Certified Milk 64 

Production of Certified JNIilk 65 

Inspected Milk 66 



CHAPTER VII. 

Pasteurized Milk 67 

Alleged Disadvantages of Pasteurization 68 

1. Promotes Carelessness 68 

2. Produces Chemical Changes 69 

3. Does not Kill all Undesirable Germs 69 

4. Toxic By-products Remain in Milk 72 

5. Covers Some Defects of ]\Iilk 72 

6. Affects Flavor and Creaming Property 72 

7. Cost of Pasteurization 73 

Advantages of Pasteurization 75 

1. Protection against Abnormal and Pathogenic Bacteria. . . 75 

2. Decreases the Total Number of Bacteria 75 

3. Pasteurized Milk Keeps Longer 77 

Pasteurization of Milk Increasing 77 

Official Supervision of Pasteurization 77 

Laws and Ordinances Pertaining to Pasteurization 78 

Home Pasteurization 79 

CHAPTER VIII. 

Modified Milk 80 

Use of Modified Milk 80 

DigestibiHty of Modified Milk 80 

1. Composition of Human Milk (Colostrum and Normal) .... 81 

2. Normal Human Milk Compared with Cows' Milk 81 

Food Requirements of Infants 82 

Methods for Modifying Milk 83 

Homogenized Milk 84 



CHAPTER IX. 

The Village Milk Plant 87 

Objectionable Practices 87 

Equipment of the Plant 8g 

1. Cooling the Milk 89 

2. Bottling the Milk 89 

3. Bottle Washing 92 



viii CONTENTS 

CHAPTER X. PAGE 

The City Milk Plant 94 

Transportation 94 

The Intake 96 

Sanitary Piping 97 

Clarifying 97 

Pasteurization and Cooling 98 

Pasteurizers 100 

Pasteurization in the Bottle ■ loi 

Bottling 104 

Delivering 105 

Bottle Washing 105 

The Milk Bottle 109 

The Bottle Cap no 

Business Principles in 

CHAPTER XL 

Standardization of Milk and Cream 114 

Standardization of Milk 115 

Standardization of Cream 119 

CHAPTER XII. 

Sanitary Examination of Milk 123 

Acidity Test , 1 23 

Sediment Test 1 24 

Leucocytes in Milk 125 

Reduction-Fermentation Test 126 

CHAPTER XIII. 

Whipping of Cream 127 

Conditions Affecting Viscosity of Cream 127 

Preparing Viscogen 127 

Use of Viscogen in Cream 128 

PART III. 

ICE CREAM MAKING. 

CHAPTER XIV. 

Ice Cream Making 132 

History and Extent of Ice Cream Making 132 

Classification of Ice Cream and Ices 135 



CONTENTS IX 
CHAPTER XV. 

PAGE 

Cream for Ice Cream Making 139 

Acidity 139 

Homogenized Cream 140 

Pasteurization 141 

Aging and Cooling 142 

Fat Content 142 

CHAPTER XVI. 

Preparing the Mix. Fillers and Binders 143 

Flavor 143 

1. Crushed Fruits 144 

2. Extracts 144 

3. Sweetening 144 

Fillers and Binders 146 

CHAPTER XVII. 

Freezing the Mix 150 

Ice and Salt 150 

Speed of Dasher 153 

Freezing Period 153 

Freezing Point 154 

EiYect of the Sugar Content on the Freezing Point 155 

Swell 155 

Stopping Point 157 

Hardening 157 

Returned Goods 157 

Fancy Ice Cream 158 

Fat Content of Different Portions 159 

CHAPTER XVIII. 

Formulas 1 60 

Vanilla Ice Cream 1 60 

Fruit Ice Cream 161 

Parfait 161 

Mousse 1 6 r 

Lacto 162 

Sherbet 162 

CHAPTER XIX. 

Ice Cream Machinery 163 

Freezers 1 65 

Ice Crusher 169 



X CONTENTS 

PAGE 

Homogenizer 169 

Sanitary Pipes and Fittings 171 

Ice Cream Can-Washer 171 

Packing Cans 171 

Sterilizer 172 

CHAPTER XX. 

Ice Cream Factories 173 

Local Creameries 1 73 

Advantages 1 74 

Cost of Equipment 175 

Profits from this Product 175 

The Large City Factory 1 76 

Homogenized Cream 176 

Making the Mix 1 78 

Freezing and Hardening 178 

Standardization of Cream 180 

CHAPTER XXI. 

Scoring Ice Cream 182 

Proposed Score Cards 182 

CHAPTER XXII. 

Ice Cream Standards 186 

Binders and Fillers 186 

Fat Standard 186 

Testing Ice Cream 188 

,. I. Hydrochloric and Acetic Acid Method 188 

2. Modified Babcock Method 189 

Bacteria in Ice Cream 189 

CHAPTER XXIII. 

Mechanical Refrigeration 193 

Chemicals Used 193 

Principles of Producing Cold Artificially 194 

Transferring the Cold 196 

Use of Brine 197 

Strength of Brine 198 

Size of Compressor 198 

Operation of an Ammonia Plant 198 

Insulation 201 



CONTENTS XI 

PART IV. 
BY-PRODUCTS OF THE CREAMERY AND CHEESE FACTORY. 

CHAPTER XXIV. pace 

Cottage Cheese 203 

Milk to Use 203 

Use of Starters 204 

Souring the Milk 204 

Heating the Curd 205 

Draining the Curd 205 

Seasoning the Curd 205 

Yield of Cheese 205 

Use of Rennet in Cottage Cheese Making 206 

Use of Hydrochloric Acid 206 

Buttermilk Cheese 207 

Heating the Buttermilk 207 

Draining the Curd 20S 

Seasoning the Curd 208 

Kind of Buttermilk 209 

Buttermilk Cream 210 

CHAPTER XXV. 

Whey Butter 211 

Original Methods of Making Whey Butter 212 

Poor Methods Employed 213 

Modern Whey Butter Making 213 

Disposal of Whey Butter 214 

Profits from Whey Butter Making 215 

CHAPTER XXVI. 

Milk Sugar 216 

History and Development of Milk Sugar Manufacturing 216 

Milk Sugar Making in the United States 217 

The Process of Manufacture 21S 

By-products of Milk Sugar Making 219 

Mysost 219 

CHAPTER XXVII. 

Casein 221 

Preparation of Casein 221 

Casein from Buttermilk 224 



Xli CONTENTS 

PAGE 

Casein Glue 225 

Casein Paints 226 

Milk-Cement Paint 226 

Plastic Masses from Casein 227 

Manufacture of Galalith 228 

Casein in the Textile Industrj' 229 

Casein Foodstuffs 230 

Casein in the Paper Industry 230 

Other Uses for Casein 231 

Buttermilk Poultry Food 231 

CHAPTER XXVIII. 

Fermented Milks vf'? 232 

Food Value 232 

Principles Involved 232 

Tablet and Capsule Cultures 233 

Buttermilk 234 

Composition 234 

Artificial Buttermilk 235 

Bacillus Bulgaricus for Buttermilk 236 

Buttermilk Tablets 237 

Kefir 238 

Kumiss 241 

American Kefir or Kumiss 242 

Yoghurt, etc 244 

Ropy Milk 245 

Moscow Sour Cream 245 

Clotted or Devonshire Cream 246 

Carbonated Milk 247 

CHAPTER XXIX. 

Condensed and Evaporated Milk 249 

Extent of the Industry 249 

U. S. Standards 250 

Quahty of Raw Product 251 

The Condensing Process 253 

Degree of Concentration 255 

Sterihzation 259 

Shaking the Canned Milk 260 

Composition of Evaporated Milk 261 

Composition of Sweetened Condensed Milk 261 

Relatively Large Investment Needed 262 



CONTENTS xiii 

CHAPTER XXX. 

Milk Powder 264 

Advantages of Milk Powder. 264 

History and Development of Milk Desiccation 265 

The Modern Method 267 

Use of Milk Powder 268 

Composition 269 

Whey Powder or Dried Whey 269 

CHAPTER XXXI. 

Renovated Butter 270 

Ladles 2 70 

Origin of Renovated Butter *'.'^ 271 

Extent of the Industry 271 

The Processes of Manufacture 272 

Melting 272 

Refining the Oil 273 

Making the Emulsion 273 

Crystallizing the Fat 273 

Working and Salting 274 

Extracts from U. S. Laws Relating to Renovated Butter 274 

Test for Renovated Butter 276 

CHAPTER XXXII. 

Oleomargarine 277 

Origin of Oleomargarine 277 

The Original Process 278 

Developments in the Industry 278 

Manufacture of Oleomargarine 279 

Formulas Used 281 

Quantity Produced 284 

Food Value 284 

Oleomargarine Law 286 

Detection of Oleomargarine 287 



DAIRY TECHNOLOGY 



PART I. 
MILK AS A FOOD. 

CHAPTER I. 

MILK — ITS PROPERTIES AND COMPOSITION. 

What is Milk? — According to the government stand- 
ard, " Milk is the lacteal secretion obtained by the com- 
plete milking of one or more healthy cows, properly fed 
and kept, excluding that obtained within fifteen days 
before and five days after calving." 

Milk is a fluid secreted by females of the mammahan 
group for the special purpose of providing their young with 
a proper food. It is a watery solution of milk sugar, albu- 
men and mineral salts, containing casein and fat in sus- 
pension. 

The only milk of great commercial importance to man 
is that of the cow. Unless otherwise specified, therefore, 
the word " milk " always refers to the product of the cow. 

Properties of Milk. — Milk ranges in color from a bluish 
white to a golden yellow, depending upon the breed of the 
animal, the food consumed, and the season of the year. 
It appears completely opaque when in large quantities, 
but in thin layers is slightly transparent. When freshly 
drawn it possesses a characteristic odor. This animal 
odor is very volatile and soon escapes from the milk, if 



2 DAIRY TECHNOLOGY 

left exposed to the air. The flavor of milk is slightly sweet- 
ish. Fresh milk has an amphoteric reaction, turns red 
litmus paper blue and blue Htmus paper red. This re- 
action, so far as known, is due to the presence of phosphates 
in the milk. Fresh milk, however, appears acid to phenol- 
phthalein, and when titrated with tenth-normal alkali 
shows an apparent acidity of from o.io to 0.14 per cent. 
This acidity is undoubtedly due to the presence in the 
milk of phosphates, citrates, casein and carbon dioxide. 

The viscosity of milk is greater than that of water. It 
is increased by age, low temperature, products of fermen- 
tation and a high solid and fat content. The viscosity 
of milk is decreased by high temperature, a low soHd and 
fat content and certain fermentations. 

Milk possesses a certain adhesive property. It sticks 
to wood, glass and metals to a greater degree than does 
water. A paper moistened with milk or cream makes a 
label that will stick to any dry object. A similar paper 
moistened with skimmed milk has less adhesive power. 
The adhesive property of milk is in part dependent upon 
the nitrogenous matter. This fact is made use of in paint- 
ing and whitewashing. The addition of milk causes the 
paint to adhere better. When milk is allowed to stand at 
room temperature, it undergoes fermentation; lactic acid 
is formed and the milk becomes thick and curdled. The 
curdUng of milk may be produced by the addition of any 
dilute acid. If the milk thus curdled is neutralized with an 
alkah, such as hme water, ammonia or potash, the curd is 
redissolved. Milk may also be curdled by rennet or pepsin, 
and the curd thus produced cannot so easily be redissolved 
by weak alkali solutions. 

Milk is sHghtly heavier than water; its specific gravity 
varies from 1.029 to 1.034 at 60° F. 



MILK — ITS PROPERTIES AND COMPOSITION 3 

The specific heat of milk is less than that of water; 
that is, it requires less heat to warm a definite amount of 
milk one degree. It also takes less ice to cool a certain 
volume of milk one degree than it does to cool the same 
quantity of water one degree. The specific heat of milk 
is, according to Fjord, 0.94; the specific heat of cream is 
about 0.7, depending upon the percentage of fat it con- 
tains. Rich cream has a lower specific heat than poor 
cream. 

The maximum density of milk is not, like water, at 
4° C. (39.2° F.), but at about 32.9° F. The boiling point 
is a trifle higher, and the freezing point a trifle lower than 
that of water. 

Composition of Milk. — Probably no other food found 
in nature, except meat, is subject to such great variation 
in composition as is milk. The average composition of 
American milk, according to Babcock,^ is: 



Water 87 

Fat.. 3 

Casein 3 

Albumen 

Sugar 4 

Ash 



The milk of individual animals varies from day to day, 
and varies as the period of lactation advances. However, 
the mixed milk from a large herd is not subject to very 
great variations, but the milk of one herd may differ greatly 
from that of another herd, due to the breed of the cattle. 
The constituents subject to the greatest variation are the 
fat and casein. The following table- shows this: 

^ Farrington and Woll — Testing Milk and Its Products. 
2 Van Slyke — Science and Practice of Cheese Making. 



DAIRY TECHNOLOGY 



Breed. 



Holstein. . 
Ayrshire. . 
Shorthorn 
Devon. . . 
Guernsey . 
Jersey .... 



Per cent 
fat. 



Per cent 
casein. 



2.46 
2.79 
3.10 
2.91 
3 03 



Per cent 
total solids. 



11.80 
12.75 
14-30 
14-50 
14.90 
15-40 



Milk from one dealer may contain 25 per cent to 40 
per cent more nutrients than milk from another dealer, 
but in the same locaHty the consumer usually pays the 
same price for both. 



CHAPTER II. 

NORMAL MILK AND ITS PRODUCTS AS FOOD. 

Food is any substance taken into and used in the body 
for the purpose of building new tissues and repairing the 
old, and for supplying the body with heat and energy. 
The best foods are those which produce the best physio- 
logical results with the least amount of waste. They 
must be hygienic, digestible, palatable, furnish the nu- 
trients needed by the system in proper amounts and be 
reasonably cheap. 

Milk, properly produced, is a food having all these 
requirements. 

There are three chief classes of nutrients necessary to 
maintain the human body: 

1. Fats, sugars, starches and cellulose. These are the 
chief food elements that produce energy, fat and heat in 
the body. Cellulose and starch are not found in milk. 
The sugar and fat are the most important ones. They 
are found in milk in sufficient and proper quantities to 
supply the body. 

2. Proteids. These chiefly produce the muscles, tendons 
and hair. They are also to some extent producers of 
energy. Good examples of the proteid group are casein 
and albumen found in milk. 

3. Mineral foods. The chief of these are phosphates, 
chlorides and other salts, calcium, potash and soda, with 
small quantities of iron and magnesia. They chiefly pro- 
duce the bones of the body. 



6 DAIRY TECHNOLOGY 

Milk contains iron and phosphorus in sufficient quan- 
tities to supply the needs of a growing individual. These 
minerals are specially needed during the period of cell 
and tissue building, the nucleus of the body cell being rich 
in iron and phosphorus. 

The water in milk is also essential to the body. Milk 
contains enough water to supply the body, providing the 
body is at rest and no dry food other than milk is con- 
sumed. 

The nutritive ratio of milk is about i: 4. While this 
ratio is a little narrow, the proportion of the different com- 
ponents is nearer perfect than in any other single food. 

Pure, sweet and wholesome milk as a food is preferred 
to any other natural food, that is, food not prepared by 
man. Originally the milk from cows was utilized solely 
for their young. Owing to man's skill in selecting and 
breeding, the qualities of dairy cows and their products 
have been regulated and developed to such an extent that 
the cow's milk serves in a large measure as a food for man. 
The speciaHzed dairy types produce large quantities of 
milk, and the richness of the milk can be regulated by 
making the proper selection of cows. 

Milk cannot be said to be a perfect food for adults, be- 
cause, in the first place, milk contains too large a per cent 
of water. As a consequence, too much bulk (8 to 11 lbs. 
daily) would have to be consumed to obtain the necessary 
nutrients. Secondly, there is a trifle too large a percentage 
of protein in milk in proportion to the fat and carbohy- 
drates (1:4). Thirdly, the milk nutrients, not including 
water, are too concentrated or condensed. A certain 
amount of bulky food is generally admitted to be necessary 
to the best digestion and health of a person or animal. 
Fourthly, a digestive system, receiving no other food than 



NORMAL MILK AND ITS PRODUCTS AS FOOD 7 

milk, is eventually Likely to lack in development, because 
of being unaccustomed to handle other foods, digested 
with greater difficulty; just as the muscles of an idle 
person, or one who does Httle work, are likely to become 
soft and weak. Milk as a food for adults is most effective 
when used in conjunction with other foods. 

The present extensive and increasing use of milk as a 
food is due chiefly to five things: 

1. Fresh milk, properly produced and handled, is 

palatable and rehshed by most people. 

2. All the chief classes of nutrients (proteids, carbo- 

hydrates and fats, and minerals) necessary for the 
development of the animal and human body are 
present in such proportions as to render milk most 
serviceable as a food. 

3. The food constituents are present in milk in such 

form as to make them easily digestible. 

4. Milk is a cheap food. 

5. Milk is a food already prepared by nature. 

Palatability of Cows' Milk. — The palatabihty of milk 
is due to the fact that the different components of milk 
are present in such a proportion as to produce a flavor 
suitable to the majority of people. It is a general principle, 
that the more volatile and soluble a substance is, the more 
easily it can be detected by the senses of taste and smell. 
Some of the natural flavoring substances in milk, though 
present in very small quantities, are volatile and soluble 
at a low temperature, so that when warmed in the mouth 
the flavor is quickly detected. Milk, in order to have its 
best flavor, should be produced from healthy cows, fed on 
food that will impart the best flavors, such as well-cured, 
good, sweet hay, grain, ensilage or roots in winter, and 



8 DAIRY TECHNOLOGY 

grass in summer. Milk is best for direct consumption as 
soon as possible after it is drawn and cooled. In case 
of specially fermented milks this does not apply. On 
standing, milk undergoes fermentation and decomposi- 
tion. The extent to which these changes occur depends 
upon the temperature at which milk is kept and upon the 
number and kinds of germs in the milk. If milk and other 
dairy products are kept, they should be held at a low tem- 
perature. Unpalatable and other abnormal milk will be 
mentioned later. 

Digestibility of Milk. - Milk, generally speaking, ranks 
high as a digestible food; but in this connection it should 
be stated that the digestibility of cows' milk varies. First, 
it varies according to the condition of the milk (whether 
fresh or old, whether adulterated or not), and according 
to the composition of the milk. Secondly, the digestibility 
of milk varies according to the power of digestion of differ- 
ent persons. Thirdly, its digestibility varies according to 
the amount consumed, and whether it is taken with other 
foods or not. 

When milk is consumed, it passes first into the stomach, 
where the acid and pepsin in the gastric juice curdle and 
dissolve it. When milk is consumed in large quantities 
at a time, without the addition of any other food, the curd 
or casein may gather in lumps. In this condition the gas- 
tric juice digests it with difficulty. Abnormal fermentation 
may set in and cause sickness before the digestive juices 
have a chance to bring the normal digestive changes about. 
This condition is especially common with infants and with 
adults having a weak digestive system. 

Human milk curdles differently from cows' milk. The 
former contains less casein than the latter, and the casein 
is probably combined with the mineral salts in a different 



NORMAL MILK AND ITS PRODUCTS AS FOOD 9 

manner. The casein of human milk is separated and more 
flocculent when curdled. In this condition the digestive 
juices attack it with greater ease. 

Pasteurized cows' milk coagulates into a more flocculent 
or separated curd than does raw milk. 

Raw vs. Heated Milk. — The effect of heat upon the 
digestibility of milk is a matter that the best authori- 
ties do not agree upon, though it has been the subject of 
considerable investigation. Heating milk to a temperature 
sufficiently high for efficient pasteurization partly renders 
the calcium salts insoluble and may partly coagulate the 
lactalbumin. But since investigators obtain different 
results in their work, it seems evident that the ease of 
digestibility of heated milk cannot differ greatly from that 
of raw milk. And, as will be shown later, the pasteur- 
ization of average city milk is beneficial. 

Use of Milk with Other Foods. — In a series of digestion 
experiments conducted by Professor Harry Snyder at the 
Minnesota Experiment Station, various foods were used 
at different times, milk constituting in many cases a con- 
siderable part of the diet. One fact of great practical 
importance brought out by this work was that the various 
foods showed a higher digestibility when milk was included 
in the diet than when fed alone. 

The food components may undergo many different 
changes in the digestive tract, depending upon the person 
and the conditions and demands of the person's system. 
The complex cleavage and synthetic changes of digestion 
and assimilation, especially during the end processes, are 
imperfectly understood. 

When the digestibiHty of the components of milk is 
compared with that of other food substances, milk ranks 
among the most digestible of all foods. 



10 DAIRY TECHNOLOGY 

According to experiments, cows' milk contains 3.6 per 
cent proteid, of whicli 3.48 per cent is digestible. It con- 
tains 4.9 per cent carbohydrates, of which 4.7 per cent is 
digestible. It contains 3.7 per cent fat, of which 3.7 per 
cent is digestible. 

Relative Cost of Milk. — The place of milk in the diet, 
its use as a substitute for other foods and the relative value 
of the nutrients it contains, as compared with the cost of 
nutrients in other foods, are not generally realized. Some 
investigations were made at the Un;iversity of Maine, ^ 
in which the effect of quantities of milk was tried at the 
university boarding house. From this investigation the 
following conclusions were drawn : i . Arttabundant supply 
of milk in the dietary decreased the cost without decreasing 
the acceptability of it to the consumer. 2. The increased 
consumption of milk increased the proportion of protein 
in the diet. 3. The consumption of large quantities of 
milk was accompanied by a decreased consumption of 
other foods. 4. Milk is not a luxury but an economical 
food that might be more widely used as a means of im- 
proving the character of the diet and of reducing the cost 
of animal foods. 

One quart of milk (2 lbs.), and three quarters of a pound 
of moderately fat beef, such as sirloin, contain about the 
same food value,^ but we pay different prices for them. 
Milk is the cheaper and comes the nearer to being a per- 
fect food. One might live on beef alone, but it would 
be a one-sided diet, while milk is more nearly a balanced 
ration. 

1 U. S. Dept. of Agr., Office of Exp. Sta. Bui. 37. 
^ U. S. Dept. of Agr., Farmers' Bui. No. 23. 



NORMAL MILK AND ITS PRODUCTS AS FOOD 



II 



TABLE WHICH SHOWS AMOUNTS OF NUTRIENTS IN A 

POUND OF MILK AS COMPARED WITH A POUND OF 

MEAT, BREAD AND OTHER FOOD PRODUCTS.^ 



Food materials. 



Refuse. 



Edible portion. 



Nutrients. 



Water. 


Protein. 


Lb. 


Lb. 


0.87 


0.03 


O.QO 


0.04 


0.91 


0,03 


0.34 


0.26 


Oil 


0.01 


61 


0.18 


0.69 


0.19 


O.S3 


0.16 


0.50 


0.14 


0.51 


0.15 


0.43 


■ 0.13 


0.44 


0.14 


0-35 


13 


0.07 


0.02 


0.48 


0.15 


0.58 


oil 


0.40 


0.16 


0.38 


0.17 


0.88 


0.06 


0.12 


O.II 


0.13 


0.09 


0.07 


0.16 


0.35 


O.IO 


0.08 


O.II 


0.13 


0.22 


0.70 


O.OI 


0.67 


0.02 


0.62 


O.OI 


0.62 


O.OI 



Fat. 



Carbo- Mineral 
hydrates, matter 



Fuel 

value. 



Milk (i pint or i pound): 

Whole milk 

Skim milk (0.3 per cent 

fat) 

Buttermilk 

Other food materials (i 
pound each): 

Cheese 

Butter 

Beef: 

Round 

Shoulder clod 

Sirloin 

Fore quarters 

Hind quarters 

Mutton, side 

Pork: 

Loin 

Ham 

Salt, fat 

Chicken 

Codfish: 

Fresh 

Salt 

Mackerel, salt 

Oysters, solids 

Wheat flour 

Com meal 

Oatmeal 

Wheat bread 

Crackers 

Dried beans 

Beets 

Potatoes 

Turnips 

Apples 



Lbs. 



0.30 
0.25 
0.23 



0.20 
o.is 
0.30 

0.2S 



Lb. 



0.34 
0.85 



0.12 

O.II 

0,17 
0,16 
0.17 

0.24 



0.2s 
0.34 
0.87 

O.OI 



0.17 
0.02 

O.OI 

0.02 
0.07 

O.OI 
O.IO 

0.02 



Lb. 
0.0s 



0.0s 
0.05 



Lb. 

O.OI 



O.OI 
O.OI 



0.04 
0.03 

O.OI 
O.OI 
O.OI 
O.OI 
O.OI 
O.OI 

O.OI 

0.04 
0.04 

O.OI 
O.OI 

0.19 
o. 10 

O.OI 
O.OI 
O.OI 

0.02 

O.OI 

0.02 
0.04 

O.OI 
O.OI 
O.OI 



Cal. 

325 



170 

165 



1965 
3605 

870 

83s 

1040 
9SO 
1000 

1275 
1340 

i6S5 
371S 
32s 

20s 
315 
1050 
23s' 
1645 
I6S5 
i860 
1 20s 
189s 
1590 
170 
325 
I3S 
255 



^ U. S. Dept. of Agr., Farmers^ Bui. No. 74. 



12 



DAIRY TECHNOLOGY 



TABLE WHICH SHOWS NUTRIENTS AND ENERGY IN ONE 

POUND OF THE WATER-FREE EDIBLE PORTION 

OF SEVERAL FOOD MATERIALS.^ 



Food materials. 



Whole milk 

Skim milk (0.3 
per cent fat) . . . . 

Buttermilk 

Cheese 

Beef, round 

Smoked ham 

Wheat flour 

Wheat bread 

Potatoes 

Apples 



Protein. 


Fat. 


Carbo- 
hydrates. 


Mineral 
matter. 


Lb. 


Lb. 


Lb. 


Lb. 


0.25 


0.31 


0-39 


0.05 


0.36 
0-33 
0-39 

0.57 
0. 26 


0.03 
0.06 
0.52 
0.40 
0.66 


O.S5 
0.53 
0.03 


0.06 
0.08 
0.06 
0.03 
0,08 


0.13 
0.15 


O.OI 

0.02 


0.85 
0.82 


O.OI 

0.01 


0. 10 
0,03 


O.OI 

0.03 


0.8s 
0.92 


0.04 
0.02 



Fuel value. 



Cal.i 
2475 

1835 
1845 
2990 
2750 

3275 
1865 
1865 
1790 
1885 



1 One calorie is the amount of heat necessary to raise the temperature of one pound 
of water \^ F. or i kilogram of water 1° C. 

The cheapest food is that which furnishes the largest 
amount of digestible and healthful nutrients at the least 
cost. The cost of one pound of round steak is about twelve 
cents; of one pound of sirloin about fifteen cents; and of 
one pound of milk about two and one half cents. In price 
five pounds of milk is equal to one pound of round steak, 
and six pounds is equal to one pound of sirloin steak. 



^ U. S. Dept. of Agr., Farmers' Bui. No. 74. 



NORMAL MILK AND ITS PRODUCTS AS FOOD 



13 



APPROXIMATE COST OF NUTRIENTS IN MILK AS 
COMPARED WITH OTHER FOOD MATERIALS.^ 





Whole milk. 


Skim milk. 


Food materials. 


Amount. 


Cost at 
6 cents 
per qt. 


Amount. 


Cost at 
.3 cents 
per qt. 


One pound of beef: 


Quarts. 

2.7 
1-3 
2.9 
1.2 
2.4 
1.6 
2.0 
2.2 

2.1 
2.1 
2.3 
5.7 
2.0 
2.5 
2.2 
OS 
2.4 
0.5 
1.9 
0.4 
1.7 
2.5 
1.4 
1.9 
3-3 
2.4 
0.3 
OS 
0,2 
0.2 


Cents. 

16 
8 
17 
7 
14 
10 
12 
13 

13 
13 

2 

34 

12 

IS 

13 

3 

14 

3 

II 

2 

10 

IS 

8 

II 

20 

14 

2 

3 

I 

I 


Quarts. 

2.7 
2.6 
2.9 

2.S 

2 4 
32 
2.0 

4-4 

2.1 
41 

3 
II. 3 

2.0 
S.o 
22 

1 
2.4 
l.o 
1.9 
0.7 
1.7 
5.0 
1.4 
3.7 
3.3 
4.8 
0.3 

I.O 

0.2 

0.4 


Cents. 
8 


Round furnishes fuel value equivalent to 

Shoulder clod furnishes protein equivalent to . . . 
Shoulder clod furnishes fuel value equivalent to. 


8 
9 
7 
7 


Sirloin furnishes fuel value equivalent to 

Mutton loin furnishes protein equivalent to 


10 
6 
13 


Pork: 


6 












34 


Smoked ham furnishes protein equal to 

Smoked ham furnishes fuel value equal to 

Chicken furnishes protein equal to 


6 

IS 
7 








7 






6 


Oysters, " solid," furnish fuel value equal to 

Wheat flour furnishes protein equal to 


2 
S 

15 


Wheat bread furnishes protein equal to 


4 






Beans, dried, furnish protein equal to 




Beans, dried, furnish fuel value equal to 


14 






Potatoes furnish fuel value equal to 


3 






Turnips furnish fuel value equal to 









5 pounds of milk worth 12 cents have a total fuel value 
of 1625 calories. 

I pound of round steak worth 12 cents has a total fuel 
value of 855 calories. 

I pound of sirloin steak worth 12 cents has a total fuel 
value of 970 calories. 

45 pounds of wheat flour worth 12 cents have a total 
fuel value of 7896 calorics. 

1 U. S. Dept. of Agr., Farmers' Bui. No. 74, 



14 DAIRY TECHNOLOGY 

3 pounds of wheat bread worth 12 cents have a total 
fuel value of 3840 calories. 

9f pounds of potatoes worth 12 cents have a total fuel 
value of 3600 calories. 

2f pounds of beans worth 12 cents have a total fuel value 
of 3876 calories. 

The prices of the different foods mentioned above vary. 
The prices prevailing in this section of the country have 
been used in making the above comparison. 

From the above statement it will be seen that the food 
value of milk is much greater than that of beef when the 
price of each is taken into consideration. On the other 
hand, wheat bread and potatoes are foods having a high 
fuel value; but both are rather one-sided rations, as may 
be seen from the preceding table giving the nutritive 
ratio. Potatoes as an exclusive diet would be undesirable 
on account of the great quantity necessary in order to get 
the required number of calories. From the analysis of 
beans, it will be seen that they form a very narrow ration, 
but when eaten with some fatty food, they are cheap. 

Fresh, normal milk is a healthful, palatable, cheap 
and easily digested food. It is owing to this that the 
demand for milk is constantly on the increase. With the 
increased production of milk for direct consumption in 
cities, great care has been exercised, and must be, in order 
to get the milk into the market in good condition. 

** If the American people would eat half less meat and 
consume one half more milk, they would save about one 
hundred and fifty millions of dollars in money, and, in 
health, enough to make the doctors' bills look small." ' 

Skim milk. — ■ The value of skim milk depends to a certain 
extent upon the method employed in separating the cream. 
^ Storrs — Cotm. Bui. No. 51. 



NORMAL MILK AND ITS PRODUCTS AS FOOD 15 

The method of separation affects the age of the skim milk 
and the per cent fat remaining in the skim milk. 

The shallow pan gravity system of creaming leaves 
from 0.3 per cent to 0.5 per cent fat in the skim milk. This 
method requires about thirty-six hours for the cream to 
rise. During this time the temperature of the milk is 
about 60° F., and in some instances higher. These con- 
ditions, although favorable for a high per cent of fat, are 
not conducive to the best quality of skim milk, as the 
various ferments are more or less active at the above- 
mentioned temperature. 

The " Cooley " or deep setting system of creaming pro- 
duces skim milk which contains about 0.2 per cent to 0.4 
per cent fat. The cream rises in about twenty-four hours, 
and during this time it is kept at from 40° to 50° F. This 
temperature is so low that the ferments have little or no 
deleterious effect on the quality of the skim milk. 

The skim milk obtained by the water-dilution method 
of separation will not be considered in this connec- 
tion. 

Most of the dairy farmers in the central west now have 
hand separators, which do more efficient skimming than 
can be accomplished by any of the gravity systems. The 
skim milk obtained by the centrifugal method, under ideal 
conditions, does not contain more than o.i per cent butter 
fat. The machines, however, are seldom operated under 
ideal conditions, and the milk is not always skimmed under 
conditions most conducive to the complete removal of the 
fat. Tests and observations by the authors warrant the 
statement that skim milk from hand separators on the farm, 
on an average, contains about 0.2 per cent fat. This 
skim milk is fresh, and many of the impurities and germs 
have been removed in the process of separation. Fresh 



l6 DAIRY TECHNOLOGY 

skim milk obtained in this manner is healthful and nutri- 
tious. The average composition of centrifugal skim milk is :^ 

Per cent. 

Water 90 ■ 25 

Fat 0.20 

Casein and albumen 3 • 60 

Milk sugar 5.15 

Ash o . 80 

Skim milk may be used profitably as a food more ex- 
tensively than it is, both in the kitchen, as an ingredient 
in cooked foods, and for direct use, as a drink. When the 
butter fat is removed, the percentage of the other milk 
components is slightly increased. The protein, sugar, 
minerals and some fat are still left. These constitute 
some of the most valuable nutrients of milk. 

In some of the older countries of Europe, skim milk is 
used daily in the kitchen. Gruels, puddings, gravies and 
soups are made by using skim milk instead of water. 
White bread dough is made from skim milk. Skim milk 
is also used very extensively as a drink in connection with 
lunches. Machines have been made and set out on the 
corners of the streets and other public places where a 
person may obtain a glass of milk by dropping a coin in 
the slot. Such machines are not at all common. When 
used, great care is necessary to keep the milk in good con- 
dition and to keep the apparatus sanitary. 

Skim milk, together with bread, furnishes a cheap, health- 
ful and nutritious lunch. It is generally assumed that an 
average-sized man doing average manual work requires 
0.28 pound of protein and enough of the other food con- 
stituents to make a total fuel value of 3500 calories per 
day.^ 

^ Snyder — Dairy Chemistry. 

2 U. S. Dept. of Agr., Farmers' Bui. No. 74. 



NORMAL MILK AND ITS PRODUCTS AS FOOD 



17 



The following meal of bread and milk furnishes nearly 
one third the nutrients required by a man per day.^ 





Protein. 


Fat. 


Carbo- 
hydrates. 


Mineral 
matter. 


Fuel 
value. 


Esti- 
mated 
cost. 


(f Lb.) 10 oz. of 
wheat bread. 

(i Lb.) I pt. of 
skim milk. . . 

Total 


Lb. 

0.062 

0.040 
0. 102 


Lb. 

0.0062 

0.0030 
0.0092 


Lb. 

0-33 

0.05 
0.38 


Lb. 

0.0062 

0.0070 
0.0132 


Gals. 
753 

175 
928 


Cents. 

3 

I 

4 





A woman and a boy between 14 and 16 years of age 
require about 0.8 the food of a man. 

A girl 1.4. to 16 years old requires about 0.7 the food of 
a man. 

A child 10 to 13 years old requires about 0.6 the food 
of a man. 

A child 6 to 9 years old requires about 0.5 the food of 
a man. 

A child 3 to 5 years old requires about 0.4 the food of 
a man. 

A child under 2 years old requires about 0.3 the food of 
a man. 

Buttermilk. — Buttermilk is an important dairy by- 
product. As most of the butter is made at creameries or 
at central points the bulk of the buttermilk is produced 
at central places, where the supply is greater than the de- 
mand. As a consequence, a large portion of it is not utilized 
at all. 

Buttermilk has, practically speaking, the same food 
value as skim milk, if during the manufacturing processes 
the buttermilk has not been adulterated. It contains 
from 0.4 to 0.8 per cent lactic acid, according to age and 
degree of ripening of the cream. This acid is produced 
* U. S. Dept. of Agr., Farmers' Bui. No. 74. 



1 8 DAIRY TECHNOLOGY 

through fermentation. About one per cent of sugar is 
required to produce the amount of lactic acid mentioned 
above. In this change of milk sugar to lactic acid, other 
by-products are simultaneously produced. The complete- 
ness with which the milk sugar is transformed into lactic 
acid depends upon the species of germs present. Butter- 
milk then contains more acid and less sugar than skim 
milk. 

It is also claimed that the casein in buttermilk is easier 
to digest, because it exists in a more soluble form, being 
partly combined with lactic acid in the form of casein 
lactate. 

Buttermilk is used extensively as a beverage. When 
the cream has been properly ripened, the buttermilk is 
not only nutritious but it is healthful. Some physicians 
prescribe it for their patients. It is widely believed that 
it may be used successfully as a remedy for kidney trouble. 

Buttermilk is used extensively as a food for hogs and 
chickens. 

The average composition of buttermilk is: ^ 

Per cent. 

Water 9° So 

Fat 0.20 

Casein and albumen 3 30 

Milk sugar 5.30 

Ash 0.70 

Cream. — Cream is the portion of milk containing 
most of the fat. It may be separated either by gravity 
or by a centrifugal separator, and to be legal, cream may 
contain from i8 to 50 per cent fat, and even more. Market 
cream normally contains 18 to 25 per cent fat. The fuel 
value of a pint of cream is about 1425 calories, more than 
four quarts of milk. However, cream is lacking in pro- 

^ Snyder — • Dairy Chemistry. 



NORMAL MILK AND ITS PRODUCTS AS FOOD 19 

tein, and is chiefly valuable as a producer of heat and 
energy, and for this purpose it is not so economical as 
butter. On account of its delicious flavor and high food 
value, cream is extensively used, chiefly in connection 
with other foods. Sweet cream is perhaps relished by 
more people than is any other one food. 

The following is a fair average composition of cream 
as found on the markets of this country : ^ 

Per cent. 

Water 66 . 41 

Fat 25.72 

Casein and albumen 3 • 70 

Milk sugar 3 . 54 

Ash 0.63 

Butter. — Butter is one of the most important sources 
of fat in our diet, one of the most palatable and easily 
digested. According to recent statistics, butter consti- 
tutes about two per cent of the total food, and furnishes 
19.7 per cent of the total fat in the average American diet. 
Its flavor depends more upon the fermentation and chemi- 
cal changes that have taken place in the cream before 
churning than upon the fat itself. However, butyrin, 
the characteristic fat of butter, imparts to good butter a 
peculiar and desirable flavor that cannot be imitated by 
any other substance. In old or highly salted butter, this 
delicate flavor is replaced by the stronger and undesirable 
flavors. 

The price of butter is not necessarily dependent upon 
its food value, but upon supply and demand, and upon 
its flavor and appearance. The best grade of butter fre- 
quently sells for 50 per cent more than the lowest grade. 

The coefficient of digestion of butter is about ninety- 
nine. This is higher than other animal fats, the latter 

^ Snyder — Dairy Chemistry. 



20 DAIRY TECHNOLOGY 

being about 95 per cent digestible. Butter is made up 
of a relatively large percentage of fats having a low melt- 
ing point. Butter has a melting point of about 33° C. 
(91.4° F.), while the fats of beef and mutton melt at 40° 
to 45° C. (109° F.), higher than the body temperature of 
man. Butter-fat globules are very minute in size, and 
hence are readily emulsified, digested and absorbed. Be- 
cause of its low melting point and its physical condition, 
butter is more easily digested than other animal fats. 

As much as a quarter of a pound of butter per day has 
been consumed by an individual and found to be readily 
absorbed. It is recommended by some physicians as a 
tonic instead of cod liver oil or similar preparations. 

Composition of Butter: ^ 

Per cent. 

Fat 82.97 

Water 13-78 

Proteids 0.84 

Milk sugar 0.39 

Ash 0.16 

Salt 1.86 

Cheddar Cheese. — Cheese is a concentrated form of 
certain constituents of milk, and hence has a high food 
value. It is a very concentrated food and gives best re- 
sults when used in combination with other and more bulky 
foods. A large number of experiments carried on by the 
Office of Experiment Stations in cooperation with the 
Bureau of Animal Industry of the Department of Agri- 
culture has shown that, when consumed even in relatively 
large amounts, cheese is very thoroughly digested and 
assimilated. The cheaper varieties of cheese usually 
contain as much food value as the higher priced kinds. 

' Storch — Richmond's Dairy Chemistry. 



NORMAL MILK AND ITS PRODUCTS AS FOOD 21 

Nutrients may, therefore, be supplied at a less cost by using 
cheeses, such as Cottage and Cheddar (American), than 
by buying the fancy and imported varieties. 

From the standpoint of the protein content alone, 
two thirds of a pound of cheese has the same food value 
as one pound of beefsteak. The fuel value of cheese is 
nearly twice that of beef. As much as a half pound of 
cheese per day may be used in the diet without any physi- 
ological disturbances. 

Composition of Cheddar Cheese : ^ 

Per cent. 

Water 36 . 84 

Protein 23 . 72 

Fat 33.83 

Ash, etc 5.61 

Cottage Cheese. — This product of the dairy, known 
also by the names " Dutch Cheese " and " Schmier Kase," 
should have a more prominent place in our diet. 

Professor Snyder of the University of Minnesota fed 
several farm laborers on the following daily ration: i.i 
pounds cottage cheese, 1.16 pounds bread, 4.12 pounds 
milk and 0.06 pound sugar. The cottage cheese supplied 
over 40 per cent of the total protein and about 28 per 
cent of the total fat of the ration. This was found to 
be a very satisfactory ration from the standpoint of 
digestibility and nutritive value. On an average, 95 per 
cent of the protein and fat and 97 per cent of the carbo- 
hydrates were digested, and 90 per cent of the energy was 
available to the body. These are approximately the same 
results as were secured when milk furnished the major 
portion of the nutrients. 

" Pound for pound, cottage cheese prepared with cream 
compares favorably in composition and digestibility with 

^ Van Slyke — Science and Practice of Cheese Making. 



22 DAIRY TECHNOLOGY 

beef and other meats. One hundred pounds of skim milk 
and 4 pounds of cream, containing 20 per cent fat, will 
make from 15 to 16 pounds or more of moist cottage cheese. 
At 2 cents per quart for skim milk and 35 cents per quart 
for cream, cottage cheese would cost about eleven cents 
per pound, and compares very favorably in nutritive 
value with meats at the same price per pound. Where 
skim milk can be procured at a low cost, cottage cheese 
is one of the most economical foods that can be used. The 
addition of cream to cottage cheese favorably influences 
both its nutritive value and its palatability without in- 
creasing the cost above that of average meats. Upon 
the farm, where milk is produced, cottage cheese is one 
of the cheapest foods that can be used."^ 

The composition of cottage cheese varies greatly, de- 
pending upon the method of manufacture, the fat content 
of the milk used, and the addition of milk or cream to the 
curd. The following is considered a fair average compo- 
sition of cottage cheese as commonly made:^ 

Per cent. 

Water 37-35 

Fat 24 . 61 

Proteids 32 . 40 

Ash S.65 

1 Minnesoic Bui. No. 92. 

* Konig — Richmond's Dairy Chemistry, 



CHAPTER III. 

ABNORMAL MILK. 

Although milk is normally such a desirable and ex- 
cellent food, it is, like other foods, subject to various 
modifications and fermentations, depending upon the con- 
ditions under which it is produced and subsequently 
handled. This abnormality may be merely a slightly 
bad odor and flavor or it may be some very marked un- 
desirable characteristic of color, consistency, odor or taste. 

Again, the milk may appear and taste perfectly normal 
but at the same time contain pathogenic organisms or 
toxic properties that may prove serious and even fatal 
to the consumer. 

Milk may acquire abnormal flavors or odors in several 
ways: The cow may be slightly sick and produce milk 
with an unusual flavor. This is usually temporary. 
Highly flavored foods such as onions or turnips, when 
eaten by the cow, may impart their flavor to the milk. 
Milk absorbs any odor that it may be exposed to, such 
as zenoleum, creolin, or other strong-smelling disinfectants, 
when used in the barn too close to milking time. Flavor 
of milk may be altered after it has been drawn, by growth 
of bacteria in it. The commonest change is the souring and 
curdling of the milk, due to a fermentation of the milk 
sugar in which the latter is broken down into lactic acid. 
This is a normal fermentation and, though not desired in 
fresh milk, is not deleterious to health. 

Poisonous Milk. — When cows eat leaves of the common 
poison ivy (Rhus toxicodendron) the toxic properties 

23 



24 DAIRY TECHNOLOGY 

may be found in the milk. Ingestion of such milk by a 
human being may cause severe gastro-intestinal trouble. 
Leaves of the common artichoke are also said to produce 
certain toxic properties in the milk which cause abdominal 
pains and diarrhea in the consumer. In a few instances, 
milk sellers unlawfully add preservatives, such as formalin. 

Colored Milk. — Milk may have a reddish color due 
to the presence of blood in the milk, or such color may 
be caused by bacterial growth. Eating certain plants 
may affect the color of the milk. Bacillus cyanogenes 
is known to have infected dairies and caused a bluish dis- 
coloration of the milk. 

Bitter Milk. — Bitter milk occasionally may be observed 
during the late stages of lactation. It may be caused by 
the cow eating lupines, wormwood, etc., or it may be the 
result of bacterial growth. 

Stringy or Ropy Milk. — Stringy or ropy milk is caused 
by a growth of bacteria that are surrounded by a gummy 
capsule. So far as known there is nothing harmful about 
this fermentation, but milk of this kind is very distasteful 
to most people in this country. Some foreign people 
consider ropy milk a desirable beverage. In some in- 
stances they produce this condition by introducing into 
the milk leaves of certain plants on which bacteria causing 
milk to be ropy arc found. Edam cheese is nearly all made 
from milk that has undergone this or similar fermentation. 
In modern factories pure cultures of this particular fer- 
ment (Bacillus HoUandicus) are propagated. 

Colostrum. — This substance, although the natural 
product of the mammary glands, is not milk according 
to our pure food laws. We may, however, from the stand- 
point of human food call it abnormal milk. Colostrum 
is a yellow, viscid fluid of abnormal milk odor, and some- 



ABNORMAL MILK 2$ 

what bitter taste. It is especially secreted as the first 
food for the young, and is adapted only to that purpose. 
The ingestion of such milk, especially by children, is apt 
to produce diarrhea, colic or other digestive disturbances. 
Some foreign people, however, after the first two days, 
use it for cooking purposes. 

General. — Until a few years ago little was known about 
the effects of bacteria and other germs. This very seri- 
ously interfered with the dairy industry. Major Alvord 
reports that in a period from 1815 to 1830, in an agricul- 
tural district in Mecklenburg, Germany, the disease of 
blueness in the milk lasted eight years, and that in earlier 
times, in the best agricultural districts of Schleswig-Hol- 
stein, butter would become cheesy and moldy for several 
months in the summer. Such defects in dairy products 
occur at the present time, but in intelligent dairy circles 
they last only a short time, as the causes of them are 
knoWn and remedies can be applied. 

We know now that the chief cause of these defects is 
the action of bacteria on the components of milk. Milk, 
when first drawn, contains gases and animal odors, which 
in a large measure may be eliminated by cooling and 
aerating it in a clean atmosphere immediately after it 
has been drawn. The aeration causes the gases to pass 
ofif, and the cooling keeps the milk in good condition and 
causes fermentation to be wholly or partly checked. Cool- 
ing milk to about 50° F. and below this temperature 
checks fermentation so that the natural sweet flavor of 
the milk can be preserved without other preservatives 
for 72 hours or longer, providing all utensils, receptacles 
and surroundings are perfectly clean. If not, the milk 
will go " off " in flavor. Milk, kept even at a low tem- 
perature, will in time lose its palatability, owing to the 



26 DAIRY TECHNOLOGY 

many forms of ferments existing in milk and to our incom- 
plete control over the fermentations. 

Generally speaking, milk properly produced and handled 
does not become abnormal. When, in special cases, 
abnormal milk is produced, it should be excluded from 
the consuming channel and measures be enforced to over- 
come the adverse conditions. 

J. H. Mohler^ describes the effect of diseased conditions 
of cows upon the hygienic qualities of the milk secreted. 
He states that any of the following-named diseases of the 
cow may seriously affect the milk, making milk from cows 
afHicted with such diseases unusable as human food: 
tuberculosis, foot and mouth disease, actinomycosis of 
the udder, anthrax, cow-pox, rabies, mammitis or garget, 
gastro-enteritis, or any condition causing a great increase 
in the leucocyte content of the milk. 

^Hygienic Laboratory, Bui. No. 56. 



PART 11. 
CITY MILK SUPPLY. 

CHAPTER IV. 

EXTENT AND IMPORTANCE OF THIS INDUSTRY. 

The distribution of fresh milk to the consumer is an in- 
dustry of great economic and hygienic importance. Its 
vastness is indicated by the following statistics gathered 
by the United States Department of Agriculture: The 
American people consume annually over a billion gallons 
of milk in its natural state, the product of nearly one-third 
of the milch cows in this country. Milk is almost as neces- 
sary in cooking as flour. Few meals are served at which 
milk and cream do not form a part. The following table 
shows the daily per capita consumption of milk in 1900 
in the fifteen largest cities of the United States.^ 

Pints. 

New York, N. Y 660 

Chicago, 111 758 

Philadelphia, Pa 466 

St. Louis, Mo 409 

Boston, Mass 1.172 

Baltimore, Md 393 

Cleveland, Ohio 482 

Buffalo, N. Y 704 

San Francisco, Cal 630 

Cincinnati, Ohio 614 

Pittsburgh, Pa 746 

New Orleans, La 275 

Detroit, Mich 7°° 

Milwaukee, Wis 691 

Washington, D. C 344 

1 U. S. Dept. of Agr., Div. of Statistics, Bui. 25. 
27 



28 DAIRY TECHNOLOGY 

Southern cities consume less milk per capita than do 
Northern cities. The following cities are reported to have 
a per capita consumption of about one pint of milk per 
day: Worcester, Mass.; Newton, Mass.; Providence, 
R. I.; Hoboken, N. J.; Minneapolis, Minn.; and Sioux 
City, la. 

The increase in the production of milk is indicated 
by the increase in the number of dairy cows, which accord- 
ing to United States statistics, are as follows in the United 
States: 

No. of cows. 

1870 10, 096, 000 

1880 12, 027, 000 

1890 IS, 953, 000 

1900 16, 292, 000 

1910 21, 801, 000 

The per capita consumption of milk is on the increase. 
As an illustration of this, let us consider the milk and cream 
supply of New York City for the past 25 years. 

Gallons. 

1885 51, 026, 660 

1890 64, 801, 190 

1895 80, 270, 400 

1900 98, 116, 920 

1902 106, 910, 940 

1908 109, 500, 000 

The increase in milk consumption has been greater than 
the increase in population, indicating that the per capita 
consumption has increased.^ 

Milk, unlike most foodstuffs, is consumed largely in an 
uncooked state. Because of this fact, milk, when not pro- 
duced and distributed under proper conditions, may be- 
come dangerous as a carrier of contagious diseases. This 

1 "Next to bread, milk is more extensively used as an article of diet than 
any other foodstuff." — (J. H. Mohler, A. M. V. M. D.) 



EXTENT AND IMPORTANCE OF THIS INDUSTRY 29 

fact, in turn, is particularly important because milk is an 
important article of diet of infants, children and many 
invalids, all of whose bodies have but slight power to re- 
sist the inroads of disease germs. 

The city of New York in 1908 consumed 438,000,000 
quarts of milk, which was produced in the States of New 
York, New Jersey, Pennsylvania, Connecticut, Vermont, 
Massachusetts, Ohio and Maryland. Some of it traveled 
350 miles by rail to reach the city. Over 5000 wagons were 
employed in distributing it to the consumers. 

The milk supply of Philadelphia is obtained from 5473 
dairy farms located in four states. 

Because of the consumption of great quantities of milk 
from such widely scattered sources, because of the use of 
milk in the uncooked state, because of its place in the diet 
of infants and invalids, because of the ease with which it 
may be contaminated with disease-producing germs, and 
because of the fact that milk forms a favorable medium 
for bacterial growth, the city milk supply is a subject of 
great importance to the entire public. The problem of 
how to insure a sanitary milk supply for a large city is 
one of the greatest with which food and health officers 
have to deal. 

Condition of the City Milk Supply in Past Years. — The 
realization of the important role that this subject plays 
in the public welfare has come only in recent years. In- 
vestigations into the condition of the milk supply of cities 
were seldom, if ever, made until about two decades ago. 
These first investigations showed conditions to be bad in 
many places. Later and more thorough investigations 
have brought out some very startling facts. 

Investigations in Illinois Cities. — An investigation of the 
milk supply of Chicago and other Illinois cities in 1905, 



so 



DAIRY TECHNOLOGY 



by J. M. Truman/ revealed a very unsatisfactory state 
of affairs. Some whole districts were found supplied with 
very good milk, but other districts, especially those supplied 
chiefly by the small milk depots, received mainly poor milk. 
A very great majority of these small milk depots were 
dirty and unsanitary; many were in dark, unclean, ill- 
ventilated cellars, where the sunlight never entered. And 
in most of these places the milk was kept in cans, dipped 
into open dishes when sold, and often carried several blocks 
through dusty streets. 

In the better portions of the city, the milk was delivered 
by large dealers from wagons, and was of good quality, 
except that in some cases an undue amount of sediment 
was found in the bottles. 

The following table shows the results of an examination 
of several hundred samples of milk obtained in Illinois 
cities : 



Number 

of 
samples. 


Per cent of 
samples below 
fat standard. 


Number 

of 
samples. 


Per cent of 

samples showing 

sediment. 


413 


32 


89 


68 


95 


20 


232 


66 


150 
95 


SO 
9 


143 
212 


68 
88 


325 


19 






Total, 1078 


Average, 27.4 


Total, 676 


Average, 73.5 



Milk and Infant Mortality. — City health authorities 
in the past were more disposed to inspect milk for 
preservatives than for cleanliness, yet the latter is as 
important as the former. No doubt children are occa- 
sionally injured by the indiscreet use of preservatives, 

^ 111. Bulletin 120. 



EXTENT AND IMPORTANCE OF THIS INDUSTRY 31 

but the number that die from the effects of milk which 
has been contaminated with undesirable ferments is 
greater. 

The death rate of any city shows that more children die 
during July and August than at any other time of the year, 
and that a large percentage of these deaths are due to in- 
testinal troubles. In general, 90 per cent of the infants 
that die are artificially fed. 

Balestre and Gileta de St. Joseph, in France, showed that 
from 1892 to 1897 in every 1000 infant deaths under one 
year of age, 385 were due to gastro-intestinal diseases. 
This was the average for the whole country. The number 
of deaths from this cause in Troyes, in 1892, was 700 per 
1000. 

In 42 cities of Germany, in 1906, the average infantile 
death rate was 198 per 1000 births. Of these, 44 per cent 
were due to diarrhea. 

The relation between infant mortality and city milk 
supply is becoming generally understood among medical 
men. The high infantile death rate, especially during the 
summer months, should not, of course, be charged wholly 
to a poor milk supply. Undoubtedly this is simply one 
factor which conspires with others to cause the high in- 
fantile death rate. 

In New York City, it was early recognized by the health 
authorities that some system of regulation of the milk 
supply must be established. The first ruling established 
a standard for the composition of dairy products. In 
1902 the New York City Department of Health made a 
comprehensive investigation of the conditions surround- 
ing the production, transportation and distribution of the 
milk supply. The market milk was, as a rule, from a 
sanitary point of view, in a bad condition. 



32 DAIRY TECHNOLOGY 

Epidemics Spread by Milk. — There are on record over 
500 epidemics of typhoid fever, scarlet fever and diph- 
theria that were traced to the milk supply. 

One ,of the worst milk epidemics on record is the 
typhoid epidemic at Stamford, Conn., in 1895. Stamford 
is a town of 15,000 population and had for some months 
been comparatively free from typhoid fever. During 
the nine days following April 14, 1895, ^6° cases were 
reported, and 24 noted as suspicious. 147 of the 160 
cases, and all of the suspected cases, used milk from one 
dairyman. Between April 15 and May 28, 386 cases 
living in 160 houses were reported. The dairy was closed 
April 21, and on May 6, just fifteen days after the sale 
of milk was stopped, the outbreak had practically subsided. 
Of the 386 cases, 352 (97.2 per cent) lived in houses taking 
milk from the same dairyman, 12 were known to have 
used this milk at a cafe supplied by him, 2 obtained it 
at a bakeshop selling the same milk, and 2 obtained it 
in other ways, making 368 cases so traced, or 95.3 per cent. 

Sources of Milk Contamination. — Similar epidemics 
of scarlet fever and diphtheria are on record, the source 
of the milk contamination being probably one of the 
following : 

1. Water supply. 

2. Hands of milker. 

3. Can, pail, cooler or other utensils. 

4. Transportation. 

5. Air and dust of stable. 

6. Bottles. 

7. Deliveryman. 

J. W. Eyre has shown by experiment that B. typhosus 
and B. diphtheriae are able to proliferate in milk. Since 
the causal organism of scarlet fever has not been isolated, 



EXTENT AND IMPORTANCE OF THIS INDUSTRY 33 

it is not known whether it may or may not multiply in 
milk. 

Bovine Tuberculosis. — Investigations have shown that 
tuberculosis of the bovine type is common in children. The 
infection may be caused by the ingestion of meat from 
tubercular animals; it may be caused by inhaling infected 
air; and in all probability it may be caused by drinking 
milk from tuberculous cows. Indeed, when we consider 
that meat is usually cooked before being eaten, while milk 
is used raw, and that children consume a relatively small 
amount of meat and a very large quantity of milk, we 
cannot but conclude that milk is the main food that dis- 
seminates this disease among children. 

In milk examined for the presence of tubercle bacilli, 
an average of 5 per cent of all samples examined in various 
cities in this country contained tubercle organisms viru- 
lent for guinea pigs. In many places the percentage was 
much higher. In Philadelphia, 14.6 per cent of the samples 
of milk examined were tuberculous. Hess found 16 per 
cent of the milk supply of New York City to contain viru- 
lent tubercle bacilli. 

Butter and cheese are of much less importance in this 
respect, but it has been shown by Mohler, Washburn, 
Rogers and Doane, that tubercle bacilli retain their viru- 
lence for six months in butter, and for eight months in 
cheese. 

Parke of New York City has found bovine tubercle 
bacilli in 26 per cent of the cases of tuberculosis in children 
under 5 years of age. 

Of the fatal cases of tuberculosis among children inves- 
tigated by the German and British tuberculosis commis- 
sions, about one-third was found to be due to the bovine 
type of bacillus. 



34 DAIRY TECHNOLOGY 

The lowest estimate made by the best authorities is that 
from 2400 to 3200 deaths are caused annually in this coun- 
try, principally among children, by bovine tubercle bacilli. 
Most authorities to-day beHeve this estimate to be too low. 
Von Behring believes that tubercular cows' milk fed to 
infants is the chief cause of tuberculosis in man. 



CHAPTER V. 

IMPROVEMENT OF THE MILK SUPPLY. 

When health authorities and the pubUc in general 
came to realize the close relationship between the milk 
supply and public health, many plans were suggested for 
improving the sanitary conditions of the product. 

The inspection and regulation of other food products 
were provided for many years before any attention was 
given to milk. 

Inspection of Dairy Farms and of Milk. — Probably 
the first legislation that pertained to the sale of milk was 
that enacted in the city of Washington in 1863. As early 
as 1873, the food inspectors of that city recognized the 
importance of the inspection of milk not only in the market 
but at the place of production. This latter point was 
not emphasized by sanitarians until about twenty years 
later. The Washington milk law of 1895 was one of the 
first to provide for a proper inspection and regulation of 
the milk supply. This law proposed to begin the milk 
inspection at the cow and to follow the product as it 
passed through the hands of the transportation company, 
the wholesaler and the retailer, to the ultimate consumer. 

This law made it the duty of the health officer of the 
District of Columbia to enforce regulations to secure 
proper water supply, drainage, ventilation, air space, 
floor space, cleaning of all dairies and dairy farms within 
the District, and the isolation of diseased cattle. No 
milk could be sold in the District except that coming from 

35 



36 DAIRY TECHNOLOGY 

inspected farms, and, although the District authorities 
could not legally go beyond their territorial limits to 
inspect cows or farms, they could refuse to admit milk 
from farms not inspected. Dairy farmers wishing to 
market their product in the District asked to have the 
agents of the health authorities inspect their dairies for 
them. 

Cost of Inspection. Many cities now have laws pro- 
viding for the inspection of dairy farms and of milk from 
the time it leaves the cow until it reaches the consumer. 
The city of Washington spends for this purpose $20,000 
annually. The Milk Commissioner of Philadelphia esti- 
mated that it would cost nearly $100,000 to inspect all 
dairy farms that contributed the 146,000,000 quarts of 
milk consumed during the year 19 10. The cost of this 
inspection amounts to about 0.07 of a cent per quart. 

Geo. M. Whitaker,^ in calculating the extra cost of 
producing clean milk, finds that, in order to increase the 
score of a dairy farm about forty-two points to seventy 
points, in a 15-cow dairy, an added expense is incurred of 
5 cents per cow per day for labor. When new or additional 
equipments are needed, the cost is still greater. Assuming 
that the cows produce from 4000 to 12,000 pounds of milk 
per year each, the added expense for labor would be about 
one-half cent to one cent per quart. For the extreme cases 
requiring new equipment, the expense would be still greater. 

Fear that the price of milk would be advanced has kept 
many a city council from passing an ordinance requiring 
adequate milk inspection, and it has also prevented health 
commissioners from enforcing such ordinances. But such 
an attitude is manifestly wrong. Even though it may cost 
a little more to produce clean milk than impure milk, the 
^ U. S, Dept, of Agr., Bu. An. Ind. An. Rept., 1909. 



IMPROVEMENT OF THE MILK SUPPLY 37 

increased cost is very slight, and, as sanitary milk is one of 
the cheapest and best foods we have, there should be no 
objection to a slight increase in price, if it be accompanied 
by an improvement in the quality. The cause of impure 
and unhygienic milk is not so much a lack of expensive 
equipment, as it is a lack of clean methods, and the presence 
of unhealthy cows. 

The Score Card. — The inspection of dairy farms and 
dairies necessitated the adoption of a score card to insure 
uniformity of reports from various inspectors. The Of- 
ficial Dairy Instructors' Association has introduced such 
a score card, that has been adopted by the Dairy Division 
of the United States Department of Agriculture, and is 
being used at the present time, sometimes in a modified 
form, in more than 60 of the larger cities of the country 
and in many smaller ones. The latest form of this score 
card is as follows: 



38 DAIRY TECHNOLOGY 

United States Department of Agriculture, 

Bureau of Animal Industry, 

Dairy Division. 



SANITARY INSPECTION OF DAIRIES. 



dairy score card. 

Adopted by the Official Dairy Instructors' Association. (Subject to revi- 
sion at future meetings.) 

Owner or lessee of farm 

P. O. address State 

Total number of cows Number milking 

Gallons of milk produced daily 

Product is retailed by producer in 

Sold at wholesale to 

For milk supply of 

Permit No Date of inspection 191 

REMARKS 



(Signed) 

Inspector. 



IMPROVEMENT OF THE MILK SUPPLY 



39 



DETAILED SCORE. 





Score. 


Methods. 


Score. 


Equipment. 


Per- 
fect. 


Allowed. 


Per- 
fect. 


Allowed. 


Cows. 
Health 


6 

2 

2 
2 

2 

4 

4 

3 
3 




Cows. 
Cleanliness of cows 

Stables. 

Cleanliness of stables 

Floor 2 

Walls I 

Ceilings and ledges . . . i 
Mangers and partitionsi 

Windows i 

Stable air at milking 


8 
6 

6 

2 

2 

3 
8 

9 




Apparently in good 

health i 

If tested with tuber- 




culin once a year and 
no tuberculosis is 
found, or if tested 
once in six months 
and all reacting ani- 
mals removed 5 

(If tested only once 




a year and reacting 
animals found and re- 


Barnyard clean and well 




moved, 2.) 


Removal of manure 
daily to field or 




Bedding i 






Temperature of stable, i 
Food (clean and whole- 


(To 50 feet from stable, 
I.) 

Milk Room. 
Cleanliness of milk room . . 

Utensils and Milking. 
Care and cleanliness of 




Water 






Clean and fresh i 






Convenient and abun- 




Stables. 






Thoroughly washed 
and sterilized in live 
steam for 30 min- 
utes S 

(Thoroughly washed 
and placed over 
steam jet, 4; thor- 
oughly washed and 
scalded with boiling 
water, 3; thoroughly 
washed, not scalded, 
2.) 
Inverted in pure air. . .3 
Cleanliness of milking. . . . 

Clean, dry hands 3 

Udders washed and 

dried 6 

(Udders cleaned with 
moist cloth, 4; 
cleaned with dry 
cloth at least IS min- 
utes before milking, 
I.) 










Free from contaminat- 
ing surroundings i 




Tight, sound floor and 

proper gutter 2 

Smooth, tight walls 






Proper stall, tie, and 




Light: Four sq. ft. of 




(Three sq. ft., 3; 2 sq. 






ft., 2; I sq. ft., i; De- 
duct for uneven dis- 
tribution.) 
Ventilation: Automatic 




(Adjustable windows, 
I.) 
Cubic feet of space for 






(Less than 500 feet, 2; 
less than 400 feet, i; 
less than 300 feet, 0; 
over 1000 feet, 0.) 







40 



DAIRY TECHNOLOGY 



DETAILED SCORE. {Continued) 





Score. 


Methods. 


Score. 


Equipment. 


Per- 
fect. 


Allowed. 


Per- 
fect. 


Allowed. 


Utensils. 
Construction and con- 


I 

I 

3 

I 

I 

I 

2 
2 




Handling the Milk. 

Cleanliness of attendants . . 

Milk removed immedi- 
ately from stable 

Prompt cooling. (Cooled 
immediately after 
milking each cow) .... 

Efficient cooling; below 
50° F 


I 
2 

2 
5 

3 
3 








Water for cleaning . . . 






(Clean, convenient, and 
abundant.) 
Small-top milking pail. . 






Facilities for hot water 
or steam 






(Should be in milk 
house, not in kitchen) 




(51° to 55°, 4; 56° to 
60°, 2.) 

Storage; below 50° F 

(51° to 55°, 2; 56° to 
60°, I.) 
Transportation; iced in 




Clean milking suits 

Milk Room. 






Free from contaminat- 
ing surroundings i 

Convenient . . i 

Construction , of milk 


(For jacket or wet 
blanket allow 2: dry 
blanket or covered 
wagon, I.) 

Total 




Floor, walls, and ceil- 
ing I 

Light, ventilation, 
screens r 




Total 


40 




60 











Score for equipment plus Score for methods — — • equals FINAL 

SCORE. 

Note i. — If any filthy condition is found, particularly dirty utensils, 
the total score shall be limited to 49. 

Note 2. — If the water is exposed to dangerous contamination or there 
is evidence of the presence of a dangerous disease in animals or attendants, 
the score shall be o. 



IMPROVEMENT OF THE MILK SUPPLY 41 

Advantages of Score Card Inspection. — The score card 
system of inspection is found to have the following good 
points : 

1. It gives the health ofificer a concise, exact report, in 
a convenient form, of all dairies marketing milk in a given 
district. 

2. The score may be used as a basis for issuing licenses. 
Dairies scoring below 50 or 60 points are in some cities 
barred from selling milk until the necessary improvements 
are made to bring their score up to standard. 

3. The health commissioner or person in charge may use 
the score card as a check on the inspectors, as these cards 
indicate exactly where each inspector has been each day 
and how much he has accompUshed. 

4. One of the greatest advantages of this method, if 
properly used, is the possibihty of bringing about improve- 
ments in the dairies by means of the publication of all 
scores. When the attention of the public is called to the 
relative scores of the various dairymen, the man with the 
low score suffers a loss of trade, while there is a big demand 
for the product of the high-scoring man. Publicity incites 
competition and is a great stimulus to the improvement 
of conditions. 

5. The card tells the inspector exactly what to look 
for, so that it is practically impossible for him to overlook 
any important point. 

6. This system is generally well received by the dairy- 
men, because it is thorough, easily understood, and abso- 
lutely fair. 

7. It enables inexperienced inspectors to do efficient 
work, because of the detailed explanations on the card. 

8. It educates the producer, points out his failings, and 
instructs him how to improve his conditions. 



42 



DAIRY TECHNOLOGY 



9, It develops better business methods on the farm, and 
usually leads to greater profits. 

10. The milk dealer is enabled to discriminate between 
producers, to locate the better dairies, and thus to secure 
a higher grade of milk. 

Results of Score-card Inspections. A report of the 
Richmond, Va., board of health, October, 1907, shows 
the improvement in dairies during six months following the 
adoption of the score-card system. 





First score. 


Last score. 


Points gained. 


Percentage 
gained. 


Average 


33-4 


56.8 


23-4 


76.8 



The following extract from the Thirteenth Report of the 
Board of Health of Montclair, N. J., shows a marked im- 
provement in dairy conditions due to the use of the score 
card: 





1906. 


1907. 


Scores. 


Number of 
dairies. 


Percentage of 
total. 


Number of 
dairies. 


Percentage of 
total. 


Below 50 

Between 70 and 100. . . . 


6 

35 


13-05 
76.09 




45 



90 



Many large dealers either require in their contracts with 
the producer that his score be up to a certain standard, or 
they pay a reduced price for milk from low-scoring dairies 
and a premium for milk from high-scoring dairies. 

This is true in Geneva, N. Y., where the city authorities 
have carried on a publicity campaign, and have used their 
influence to induce the milk dealers to buy from the pro- 



IMPROVEMENT OF THE MILK SUPPLY 



43 



ducer on the basis of the score placed upon the dairy by the 
city inspector. At the beginning of this campaign, condi- 
tions were about the same as are found in many small 
cities, and the improvement from time to time may be 
noted in the following table: 



Percentage of dairies. 



Excellent. 



©ood. 



Medium. 



Poor. 



Beginning 

End of first year 

End of second year 

End of third year 

ist quarter of fourth year. . . 



■ 5-0 
:58.9 
82.8 

74-4 
87.2 



57-5 
38.2 

8.6 
12.8 

o 



37-5 



Inspection of City Milk Plants. — In the larger cities there 
is, in most instances, a middle man between the producer 
and the consumer. At the place of business of this middle 
man, the milk may simply be cooled and loaded into wagons 
for distribution, or it may be clarified, pasteurized and 
standardized; it may be a small place with but little equip- 
ment or it may be a huge building containing much ex- 
pensive apparatus. In either case, there is necessity for 
supervision by the board of health, and the following 
score card has been devised for this purpose by the Dairy 
Division of the United States Department of Agriculture: 



44 



DAIRY TECHNOLOGY 



SANITARY INSPECTION OF CITY MILK PLANTS. 



Equipment. 



Score. 



Per- 
fect. 



Allowed. 



Methods. 



Score. 



feet" Allowed. 



Plant: 

Location 

Convenience 6 

Surroundings .... 12 

Arrangements 

Proper rooms .... 3 

Convenience 4 

Constructions 

Floor 5 

Walls 3 

Ceiling i 

Light 

Ventilation 

Screens 

Machinery and uten- 
sils 

Kind and quality, 7 
(Steam or hot 
water bottle 
and can wash- 
er, bottling 
machine, dry- 
ing racks, 
crates, sinks, 
pasteurizer, 
cold storage.) 

Condition 7 

Arrangement .... 6 
Water for cleaning. . . , 
Wagons: 
Construction, con- 
dition 

Salesroom 

Location 4 

Construction .... 4 
Equipment 3 



Additional Deductions. 
For exceptionally bad 
conditions: 



Plant: 

Cleanliness 

Floor 6 

Walls 4 

Ceilings i 

Doors I 

Windows i 

Good order i 

Free from odors i 
Machinery and utensils: 

Cleanliness 

Milk: 

Handling 

(Clarifying, pas- 
teurizing, cool- 
ing, bottling). 

Storage 

45° F. or below. . .20 
45° F. to 50° F....IS 
50° to 55° F 10 



Wagons 

cleanliness 3 

Protection of prod- 
uct 3 

Salesroom: 
Cleanliness 



Additional Deductions. 
For exceptionally bad 
conditions: 



Total deductions . 
Net total 



Total deductions . 
Net total 



Score for methods — 

Score for equipment . . . 

Total, to be divided by 3. 
Final Score 



multiplied by 2 . 
multiplied by i . 



IMPROVEMENT OF THE INIILK SUPPLY 



45 



Milk and Cream Contests. — ^Another method of arous- 
ing competition and inciting dealers to deliver the best 
quahty, is the holding of milk and cream contests. These 
contests are usually given great pubhcity. Hence they 
form excellent advertisements for the dairymen participat- 
ing, and particularly profitable advertisements for those 
who make a good showing in the contest. 

The first milk and cream contest in this country was held 
at the National Dairy Show in 1906, under the supervision 
of the Dairy Division of the United States Department of 
Agriculture. The object of the contest was, first, educa- 
tional; second, to determine the possibilities of long-dis- 
tance shipments and long holdings of milk produced under 
sanitary conditions and kept cold; third, to test the ef- 
ficiency and practicability of a score card for this class of 
dairy products. Milk was sent to this contest from thir- 
teen different states, and it was here demonstrated that 
clean milk, held at a low temperature, can be shipped a 
thousand miles and be kept sweet for a period of over five 
weeks. 

Since that time, states and cities have employed the milk 
and cream contest with very gratifying results. 

The score card used is as follows: 

SCORE CARD FOR MARKET MILK. 



Exhibitor. 



Address. 



NUMERAL SCORE. 



Flavor, 
40. 


Composition, 

25. 


Bacteria, 
20. 


Acidity, 
5. 


Appearance of 
package and 
contents, lo. 


Perfect score, 
100. 












Judge's score. 



46 



DAIRY TECHNOLOGY 



DESCRIPTIVE SCORE. 



Flavor. 


Composition. 


Bacteria. 


Acidity. 


Package and 
contents. 




Perfect. 

/Fat, — per 
( cent. 


Perfect. 

Total 

Liquefiers. 
1 


Perfect. 

(-per j 
) cent. ( 


Perfect. 


Good 




Fair 




Bad 




Flat.. 


Metal parts. 


Bitter 


1 Solids, not 
> fat, — per 
) cent. 










) 














Smothered 

















Remarks . 
Date 



. , Judge. 



Directions for Scoring 

Flavor. 

If rich, sweet, clean, and pleasant flavor and odor, score perfect (40). 
Deduct for objectionable flavors and odors according to conditions found. 

If 3.25 per cent fat or above and 8.5 per cent solids not fat or above, 
score perfect (25). Deduct i point for each one-fourth per cent fat below 
3.25 and I point for each one-fourth per cent solids not fat below 8.5. 

Baclcria. 

Less than 10,000 per cubic centimeter (perfect) 20 

Over 10,000 and less than 25,000 per cubic centimeter 19 

Over 25,000 and less than 50,000 per cubic centimeter 18 

Over 50,000 and less than 75,000 per cubic centimeter 17 

Over 75,000 and less than 100,000 per cubic centimeter 16 

Deduct I point for each 25,000 above 100,000 

When an unusually large number of hquefying bacteria are present, 
further deduction should be made according to conditions found. 

Acidity. 
If 0.2 per cent or below, score perfect (5). Deduct i point for each o.oi 
per cent above 0.2 per cent. (If Mann's test is used, discontinue adding 
indicator on first appearance of a pink color.) 

Appearance of Package and Contents. 
If a package is clean, free from metal parts, and no foreign matter can 
be detected in the contents, score perfect (10). Make deductions accord- 
ing to conditions found. 



IMPROVEMENT OF THE MILK SUPPLY 47 

Such contests greatly improve the milk supply if the 
consumer is interested in the project and is willing to pay 
a slightly higher price for milk of good quality than for 
that of poor quahty. 

Number of Inspections Made in New York City. — Dur- 
ing the year 1908, there were inspected and rated on a score 
card, 41,937 dairy farms that sell milk in New York City. 
Inspectors within the city examined 101,049 specimens 
of milk, and took 6268 samples for chemical analysis, 
and about the same number for bacteriological examina- 
tion. 26,500 quarts of milk were destroyed for being 
above 50° F., and the total milk destroyed by inspectors 
for all reasons was 43,140 quarts. 

Limitations of General Inspection. — Whenever a sys- 
tem of inspection is properly carried out, many improve- 
ments may be noted in the sanitary condition of farms, 
dairies, and depots. However, in spite of the continuous 
and thorough inspection in New York City, 16 per cent 
of the samples analyzed were found to be below standard, 
and 25 per cent of the samples examined bacteriologically 
contained over 1,000,000 bacteria per cubic centimeter. 
The dairy farms inspected and scored in New York City 
in 1908 showed the following condition: 

2,179 dairies scored between 76 and 100. 
24,130 dairies scored between 51 and 75. 
15,628 dairies scored below 50. 
Average score — 57. 

A similar inspection and scoring, in New York City, of 
creameries, or places where milk is handled, revealed a 
somewhat better condition. 

613 creameries scored between 76 and 100. 
671 creameries scored between 51 and 75. 
162 creameries scored below 50. 
Average score — 71. 



48 DAIRY TECHNOLOGY 

It is evident from these figures that there is still room 
for improvement. However, although the object of city 
milk inspection is to improve the general sanitary con- 
dition of the milk supply, this general inspection does not 
aim, nor is it in itself sufficiently thorough, to insure a 
product absolutely pure and sanitary and safe for invahd 
or infant feeding. The good will and cooperation between 
health officers and dairymen for the mutual good of all is 
essential. 

Classes of Milk. — The general milk supply of many 
cities is divided into classes according to certain standards, 
such as the degree of sanitation observed in the production 
and handling of the milk, the treatment of milk before 
delivering (pasteurization), or the amount of supervision 
by health authorities. 

All milk in New York City must be sold under the follow- 
ing grades or designations in accordance with the regula- 
tions adopted by the Board of Health: 

Milk. — This term shall be applied to cows' milk which 
conforms to the requirements of the Sanitary Code and 
which does not meet the requirements of milk sold under 
other grades or designations herein provided for. 

Selected Milk. — The minimum requirements are as 
follows : 

1. Only such cows shall be admitted to the herd as 
are free from all diseases of the udder, and from clinically 
manifest tuberculosis. 

2. That all the cows be examined clinically each year 
by a veterinarian of the Department of Health; all cows 
with any disease of the udder, or with clinically manifest 
tuberculosis, to be excluded from the herd and farm. It 
shall be unlawful to sell or use the milk from such cows 
for food purposes. 

3. That the milk shall never contain more than 60,000 



IMPROVEMENT OF THE ISIILK SUPPLY 49 

germs per cubic centimeter in winter, nor more than 
100,000 germs per cubic centimeter in summer. 

4. That such milk be dehvered to the consumer only 
in sealed bottles, which shall have been filled at the dairy 
or creamery, and shall be labeled with the date of the earli- 
est milking whose milk forms part of the contents of the 
bottle. 

5. That such milk be delivered to the consumer within 
thirty-six hours after milking. 

Inspected Milk. — Which milk produced under the 
supervision of a Milk Commission appointed by the Med- 
ical Society of the County of New York or by the Medical 
Society of the County of Kings, or under certificates 
for " Inspected Milk," issued by said Commission. No 
milk, however, shall be held, kept, offered for sale or sold 
and delivered as inspected milk in the City of New York 
which is produced under requirements less than those of 
the said Board of Selected Milk. 

Guaranteed Milk. — The minimum requirements are as 
follows : 

1. That only such cows be admitted to the herd as have 
not re-acted to a diagnostic injection of tuberculin. 

2. That all such cows be tested annually with tuberculin, 
and all re-acting animals be excluded from the herd. 

3. That the milk shall not contain more than 30,000 
germs per cubic centimeter when delivered to the consumer. 

4. That the milk be delivered to the consumer only in 
sealed bottles which shall have been filled at the dairy, 
and shall bear a label giving the name of the dairy, and the 
date of the earliest milking at which the milk forming part 
of the contents was drawn. 

5. That such milk be delivered to the consumer within 
thirty-six hours. 

Certified Milk. — Which is milk certified by the Milk 
Commission appointed by the Medical Society of the 
County of New York or the Medical Society of the County 
of Kings as being produced under the supervision and in 
conformity with the requirements of that Commission 



50 DAIRY TECHNOLOGY 

as laid down for Certified Milk. No milk, however, shall 
be held, kept, offered for sale or sold and delivered as 
Certified Milk in the City of New York which is produced 
under requirements less than those of the said Board for 
Guaranteed Milk. 
Pasteurized Milk : — 

1. Pasteurization of milk must be carried out under a 
permit therefor issued by the Board of Health, in addition 
to the usual permit for milk required by Section 56 of the 
Sanitary Code. 

2. The milk after pasteurization must be at once cooled 
and placed in sterilized containers, and the containers 
sealed. 

3. All containers in which pasteurized milk is delivered 
to the consumer shall be plainly labeled " pasteurized." 
The labels must also bear the date and hour when the 
pasteurization was completed, the degree of the heat, 
and the length of time exposed to the heat, and the name 
of the dealer. 

4. Pasteurized milk must be delivered to the consumer 
within twenty-four hours of the pasteurization. 

5. No milk shall be pasteurized a second time. 

6. No milk which contains an excessive number of 
bacteria shall be pasteurized. 

The classification of market milk into the following 
three grades is suggested by the Bureau of Animal Indus- 
try, United States Department of Agriculture. A fourth 
grade is added by the authors. 

1. Certified Milk. 

2. Inspected Milk. 

3. Pasteurized Milk. 

4. Modified Milk. 

The use of these terms is recommended to be limited 
to the following: 

Certified milk is the product of dairies that are subject 
to periodic inspection by a medical milk commission, 



IMPROVEMENT OF THE MILK SUPPLY 5 1 

the products of such dairies being subject to frequent 
chemical and bacteriological examination. The cows, 
barns, milk house, utensils and milkers must come up to 
a very high standard of sanitation. The manner of hand- 
ling the milk, its chemical composition and bacterial con- 
tent are carefully prescribed. It is certified, by an author- 
ized officer, to be absolutely pure and sanitary. 

Inspected milk is produced and handled under condi- 
tions similar to those under which certified milk is pro- 
duced and handled, but to not quite so higH a degree of 
perfection, and the product is not certified to by a milk 
commission, or an authorized health officer. 

Pasteurized milk, though clean and fresh, is of less 
known origin, and is subjected to heating to a temperature 
of 150° F. for 20 minutes, or 160° F. for 10 minutes, and 
immediately cooled to a temperature not exceeding 50° F. 

Modified milk is sanitary milk, the composition of 
which is modified to conform with the food requirements 
of persons unable to use milk in its natural state. Such 
modification should be done under supervision of, or by 
prescription of, a physician or milk expert. 

Results of the Improvement of Milk Supply. — The 
chief purpose of our present-day extensive milk inspection 
and the establishment of various grades of milk is to supply 
a sanitary cheap food and to save lives. The success 
of such inspections must then be measured by their effi- 
ciency in accomplishing these ends. 

The milk-inspection service has lessened the danger of 
severe epidemics of contagious diseases due to milk in- 
fection. The most important and extensive service ex- 
pected of milk inspection is to diminish the mortality 
from diarrheal diseases of children under two years of 
age. In Washington, D. C, the death rate from diarrhea 



52 DAIRY TECHNOLOGY 

and enteritis among infants during the fiscal year following 
the enactment of the milk-inspection law in 1895, was 
168 per 100,000 of population. The next year it fell to 151 ; 
the third year to 136; and the fourth year to no. In 
1903 it was 91; in 1905, 104; in 1906, 97. 

Infants' Milk Depots in New York. — The improve- 
ment of milk supply by pasteurization is demonstrated 
by the reports of the Nathan Straus depots and the orphan 
asylum on RandaU's Island, New York City. 

In 1893, Nathan Straus established a depot for the dis- 
pensing of pasteurized milk for infant feeding. In this 
year 34,400 bottles of milk were dispensed; in 1906, 17 
Straus stations dispensed 3,142,253 bottles and 1,078,405 
glasses of pasteurized milk. 

Just prior to the beginning of this work by Straus, the 
death rate of children under 5 years of age in New York 
City was 96.2 out of every 1000. In 1906 the death rate 
had fallen to 55 per 1000, due, in a large measure, to the 
improvement of the milk supply by pasteurization. 

At the rate of mortality of 1892, there would have been 
27,169 deaths of children under 5 years of age in 1906, 
instead of the 15,534 that actually occurred. A general 
milk inspection was in operation at this time, and no doubt 
had some part in reducing the death rate. There were 
other agencies at work which contributed toward accom- 
plishing the same results, such as the campaign of fresh 
air for children, use of diphtheria antitoxin, improved tene- 
ment houses, etc. 

The efficiency of pasteurization under commercial con- 
ditions is indicated in the following data collected in Chi- 
cago in 1909. A bacterial examination of 829 samples 
of milk during seven weeks ending September, 1909, 
showed that the unpasteurized milk contained 5,547,502 



IMPROVEMENT OF THE MILK SUPPLY 53 

bacteria per cubic centimeter and the pasteurized 944,465. 
It is probable that practically all bacteria in the vege- 
tative condition (this includes all pathogenic organisms) 
were destroyed. 

At the present time the Bureau of Municipal Research 
has charge of the pure-milk crusade, and the lowering of 
the infant death rate in New York City. During some 
of the hot weeks of the summer of 191 1 the Bureau had 
about 5000 babies under its direct care. 

Seventy-live milk depots form the centers from which 
this extensive work is carried on. At the depots are 250 
trained nurses who distribute sanitary milk, prescribe for 
babies and advise and teach mothers how to feed and 
care for their children. Physicians are in attendance at 
the depots at certain hours during the day to attend to 
the more serious cases. 146 visiting nurses go to the 
houses where there are young children, and teach the 
mothers home sanitation, and influence them to procure 
from the depot whatever milk may be necessary for the 
children. 

It is here demonstrated that the distribution of clean 
milk combined with the education of mothers is one of 
the most economical and efhcient methods of reducing 
infant mortality. 

Milk Depots in Other Cities. — The first definite im- 
provements in any milk supply were made by a few insti- 
tutions that prepared and dispensed a sanitary product 
for infant feeding. Probably the first of these institu- 
tions in this country was the Eastern Dispensary of New 
York City, which, in 1S89, dispensed sanitary milk for 
infant feeding. 

Since that time, about three hundred infants' milk 
depots, as they have come to be known, have been opened 



54 DAIRY TECHNOLOGY 

in some thirty cities in this country. Many of these are 
supported by private philanthropy, others by a city board 
of health or board of charities. In all cases they are 
under the supervision of persons quaHfied to attend to 
the bacterial, chemical and sanitary condition of the 
milk. The milk of various depots is certified, pasteurized 
or modified, and in several cases two of these classes of 
milk are supplied from the same depot. The milk is 
commonly put up in bottles containing but one feeding, 
which bottles are so designed that they cannot stand on 
end and, therefore, cannot be left standing open. Milk 
of widely different formulas is put up at these depots; 
the following is taken as an example: 

Milk ounces, 64 

Limewater « 4 

Milk sugar « 6 

Filtered water « 60 

The infants, in the care of New York City authorities 
were fed on milk from carefully selected herds. The 
death rate among these infants, for the years 1895 to 1897 
inclusive, was 41.8 per cent. Early in 1898, a pasteurizing 
plant was installed. No other change in hygiene or diet 
was made, but the death rate dropped to 19.8 in 1898 
and averaged 21.75 fo^ the succeeding six years. 

Investigations of the cause of the high death rate among 
infants and young children have revealed, in numerous 
instances, that the number of deaths among children 
bears a direct relation to the quality of the milk consumed. 
Money spent to improve the milk supply buys and saves 
the Hves of many infants. It is cheaper for even the 
poorest people to pay a higher price for a high-grade milk 
than to buy an unsanitary product for a cent or two less 
per quart. 



CHAPTER VI. 

CERTIFIED MILK. 

Investigations show that market milk is improved by- 
general inspection, and that, by grading or classifying, 
some milk of very high quality can be brought upon the 
market. For a general supply of milk to be used by healthy 
adults or in cooking, the problem is not so great, because 
probably no great harm will come from the use of 




Fig. I. — Interior \aew of South Dakota State College dairy barn, showing 
clean cows in a clean, well-ventilated and comfortable place. 

ordinary market milk produced in compliance with our 
present laws and regulations. But for invalid or infant 
feeding, a much better quality is necessary. 

Origin of the Term " Certified Milk." — This term, 
so far as known, was coined by Dr. Henry L. Coit of 
Newark, N. J., who was perhaps the foremost man in the 

55 



56 DAIRY TECHNOLOGY 

originating and establishing of the first milk commission. 
The term was registered in the United States Patent 
Office to protect it from being degraded by dairymen not 
producing milk mider supervision of a medical commission. 
Some states have passed laws limiting the use of this term 
to milk of sufficiently high quality to come up to Dr. Coit's 
standard for certified milk. 

Certified milk is sanitary milk produced under the 
strict supervision and according to rules of some health 
authorities. The herd producing the milk is examined as 
to Its healthfulness at intervals. The sanitary condition 
of barn and all surroundings, bacterial content and age 
of milk are carefully watched. If these conditions come 
up to the standard the owner of the place receives a cer- 
tificate showing that he is authorized to sell his milk as 
certified milk. 

Certified milk has all the qualifications of a perfectly 
sanitary and hygienic food but the price is so high as to 
be almost prohibitory for the mass of common people. 
The only alternative seems to be pasteurized milk. This 
can be supplied at a reasonable cost and, if properly pasteur- 
ized, will be practically as sanitary and hygienic as certified 
milk. However, it is very necessary that the pasteuriza- 
tion be properly done, and to insure this all pasteurizing 
plants should be carefully and frequently inspected by 
competent authorities. 

The quantity of certified milk produced in this country 
is less than one per cent of the total amount of market 
milk annually consumed. Nevertheless, this product is 
of very great value in feeding infants and invalids; it 
has aided in reducing the death rate among children and 
has had an indirect beneficial influence upon the general 
milk supply. 



CERTIFIED MILK 57 

The First Medical Milk Commission. — In the year 1890 
the Medical Society of New Jersey started a movement to 
effect an improvement in the milk supply, which resulted 
in the formation of " The Medical Milk Commission of 
Essex County, New Jersey." Since that time many others 
have been formed in various cities upon a similar plan. 

Milk Commissions. — A milk commission usually con- 
sists of from 5 to 12 men, as a rule physicians, but some- 
times including business men who are interested in the 
welfare of the city. This board serves without pay; but 
the chemist, bacteriologist and veterinarian, who do the 
inspecting, commonly receive a fee. The first commission 
and several of the later ones formed contracts with the 
producers, wherein were exact specifications for all the 
details of the dairy and its management. However, most 
of the present-day commissions simply fLx the required 
standard and leave the details of the work to the dairy- 
men's judgment. The conditions surrounding the pro- 
duction and handling of the milk are necessarily about as 
good as the commission could demand, or it would not be 
possible to keep the milk up to the high standard required. 

Requirements of the Milk Commission of New York 
City. — In New York City no contract is made with the 
dairymen, but a circular is sent them giving information 
concerning the production, standards and general re- 
quirements of certified milk. This circular reads as 
follows : 

The commission has fixed upon a maximum of 30,000 
germs of all kinds per cubic centimeter of milk, which 
must not be exceeded to obtain the endorsement of the 
commission. This standard must be attained solely by 
measures directed toward scrupulous cleanliness, proper 
cooling, and prompt delivery. 



58 DAIRY TECHNOLOGY 

The milk certified by the commission must contain not 
less than 4 per cent of butter fat on the average, and have 
all other characteristics of pure, wholesome milk. 

Milk must not be sold as certified more than twenty-four 
hours after its arrival in New York City. 

Dealers. In order that dealers, who incur the expense 
and take the precautions necessary to furnish a truly clean 
and wholesome milk, may have some suitable means of 
bringing these facts before the public, the commission 
offers them the right to use caps on their milk jars stamped 
with the words: " Certified by the Milk Commission of the 
Medical Society of the County of New York." The dealers 
are given the right to use these certificates when their 
milk is obtained under the conditions required by the 
commission and conforms to its standards. 

In accordance with a law passed at the last legislature, 
the word, " Certified," may be used on the cap only when 
accompanied by the name of the society which certifies it. 

The tinned sealed cap, authorized by the commission, 
must be used on all the certified milk passing through the 
hands of dealers selling milk other than the certified. These 
caps are sent by the makers, only to the farm where the 
milk is bottled. 

The name of the farm from which the milk comes must 
appear on either the paper cap or the tin cap. 

Each bottle of milk must be dated on the date of bot- 
tling. 

The milk commission looks to the dealers for its fee. 

The dealer is expected to send a bottle of milk each week 
to the research laboratory of the department of health, 
taken at random from the day's supply for examination, 
by experts for the commission. 

The dealers are to furnish deep, covered boxes for the 
certified milk. 

The required conditions at the farm are as follows: 

I. The Barnyard. — The barnyard should be free from 
manure and well drained, so that it may not harbor stag- 
nant water. The manure which collects each day should 
not be piled close to the barn, but should be taken several 



CERTIFIED MILK 59 

hundred feet away. If these rules are observed not only 
will the barnyard be free from objectionable smell, which 
is an injury to the milk, but the number of flies in the 
summer will be considerably diminished. These flies are 
an element of danger, for they are fond of both filth and 
milk and are liable to get into the milk after having soiled 
their bodies and legs in recently visited filth, thus carrying 
it into the milk. 

2. The Stable. — In the stable the principles of cleanliness 
must be strictly observed. The room in which the cows 
are milked should have no storage loft above it; where 
this is not feasible the floor of the loft should be tight, to 
prevent the sifting of dust into the stable beneath. 

The stables should be well ventilated, lighted, and 
drained, and should have tight floors, preferably of cement, 
never of dirt. 

They should be whitewashed inside at least twice a year, 
unless the walls are painted or of smooth cement finish 
which can be washed frequently. 

The air should always be fresh and without bad odor. 
A sufficient number of lanterns should be provided to en- 
able the necessary work to be properly done during the dark 
hours. The manure should be removed twice daily, except 
when the cows are outside in the fields the entire time be- 
tween the morning and afternoon milkings. The manure 
gutter must be kept in a sanitary condition. All sweeping 
must be finished before the grooming of the cows begins, 
so that the air may be free from dust at the time of milking. 

There should be an adequate supply of warm and cold 
water and the necessary wash basins, soap, and towels. 

3. Water Supply. — The whole premises used for dairy 
purposes, as well as the barn, must have a supply of water 
absolutely free from any danger of pollution with animal 
matter and sufficiently abundant for all purposes and easy 
of access. 

4. The Cows. — No cows will be allowed in the herd 
furnishing certified milk except those which have success- 
fully passed a tuberculin test. All must be tested at least 
once a year, by a veterinarian approved by the milk com- 



6o DAIRY TECHNOLOGY 

mission. Any animal suspected of being in bad health 
must be promptly removed from the herd and her milk re- 
jected. Do not allow the cows to be excited by hard driv- 
ing, abuse, loud talking, or any unnecessary disturbance. 

Feed. — Do not allow any strongly flavored food, like 
garlic, to be eaten by the cows. When ensilage is fed, it 
must be given in only one feeding daily, and that after the 
morning milking, and the full ration shall consist of not 
more than 20 pounds daily for the average-sized cow. 
When fed in the fall, small amounts must be given and the 
increase to the full ration must be gradual. 

Corn stalks must not be fed until after the corn has 
blossomed, and the first feedings must be in small amounts 
and the increase must be gradual. 

If fed otherwise, ensilage and corn stalks are liable to 
cause the milk to affect children seriously. 

Cleaning. — Groom the entire body of the cow daily. 
Before each milking wash the udder with a cloth used only 
for the udders, and wipe it with a clean, dry towel. Never 
leave the udder wet, and be sure that the water and towel 
are clean. The tail should be kept clean by frequent 
washing. If the hair on the flanks, tail, and udder is 
clipped close and the brush on the tail is cut short, it will 
be much easier to keep the cow clean. 

The cows must be kept standing after the cleaning until 
the milking is finished. This may be done by a chain or a 
rope under the neck. 

5. The Milkers. — The milker must be personally clean. 
He should neither have nor come in contact with any con- 
tagious disease while employed in handling the milk. In 
case of any illness in the person or family of any employee 
in the dairy, such employee must absent himself from the 
dairy until a physician certifies that it is safe for him to 
return. 

In order that the milk commission may be informed as 
to the health of the employees at the certified farms, the 
commission has had postal cards printed to be supplied 
to the farms, and to be filled out and returned each week 
by the owner, manager, or physician of the farm, certifying 



CERTIP^IED MILK 6l 

that none are handling the milk who are in contact with 
any contagious disease. 

Before milking, the hands should be washed in warm 
water with soap and nail brush and well dried with a clean 
towel. On no account should the hands be wet during 
milking. 

The milkers should have light-colored, washable suits, 
including caps, and not less than two clean suits weekly. 
The garments should be kept in a clean place, protected 
from dust, when not in use. 

Iron milking stools are recommended, and they should 
be kept clean. 

Milkers should do their work quietly and at the same 
hour morning and evening. Jerking the teat increases 
materially the bacterial contamination of the milk and 
should be forbidden. 

6. Helpers Other than Milkers. — All persons engaged in 
the stable and dairy should be reliable and intelligent. 
Children under 12 should not be allowed in the stable or 
dairy during milking, since in their ignorance they may do 
harm, and from their liability to contagious diseases they 
are more apt than older persons to transmit them through 
the milk. 

7. Small Animals. — Cats and dogs must be excluded 
from the stables during the time of milking. 

8. The Milk. — All milk from cows 60 days before and 
10 days after calving must be rejected. 

The first few streams from each teat should be discarded 
in order to free the milk ducts from the milk that has re- 
mained in them for some time and in which the bacteria 
are sure to have multiplied greatly. If any part of the 
milk is bloody or stringy or unnatural in appearance, the 
whole quantity yielded by that animal must be rejected. 
If any accident occurs in which a pail becomes dirty, or 
the milk in a pail becomes dirty, do not try to remove the 
dirt by straining, but put aside the pail, and do not use the 
milk for bottling, and use a clean pail. 

Remove the milk from each cow from the stable im- 
mediately after it is obtained to a clean room and strain 



62 , DAIRY TECHNOLOGY 

through a steriHzed strainer of cheese cloth and absorbent 
cotton. 

The rapid coohng is a matter of great importance. The 
milk should be cooled to 45° F. within an hour and not 
allowed to rise above that as long as it is in the hands of 
producer or dealer. In order to assist in the rapid cooling, 
the bottles should be cold before the milk is put into them. 

Aeration of milk beyond that obtained in milking is 
unnecessary. 

9. Utensils. — All utensils should be as simple in con- 
struction as possible, and so made that they may be 
thoroughly sterilized before each using. 

Coolers, if used, should be sterilized in a closed sterilizer, 
unless a very high temperature can be obtained by the 
steam sent through them. 

Bottling machines should be made entirely of metal with 
no rubber about them, and should be sterilized in the closed 
sterilizer before each milking, or bottling. 

If cans are used, all should have smoothly soldered joints, 
with no places to collect the dirt. 

Pails should have openings not exceeding 8 inches in 
diameter, and may be either straight pails, or the usual 
shape with the top protected by a hood. 

Bottles should be of the kind known as " common sense" 
and capped with a sterilized paraffined paper disk, and the 
caps authorized by the commission. 

All dairy utensils, including the bottles, must be thor- 
oughly cleansed and sterilized. This can be done by first 
thoroughly rinsing in warm water, then washing with a 
brush and soap, or other alkaline cleansing material, and 
hot water, and thoroughly rinsing. After this cleansing 
they should be sterilized by boiling, or in a closed sterilizer 
with steam, and then kept inverted in a place free from dust. 

10. The Dairy. — The room or rooms where the utensils 
are washed and sterilized and the milk bottled should be 
at a distance from the house, so as to lessen the danger of 
transmitting through the milk any disease v/hich may occur 
in the house. 

The bottling room, where the milk is exposed, should be 



CERTIFIED MILK 63 

SO situated that the doors may be entirely closed during 
the bottling and not opened to admit the milk nor to take 
out the filled bottles. 

The empty cases should not be allowed to enter the 
bottling room nor should the washing of any utensils be 
allowed in the room. 

The workers in the dairy should wear white washable 
suits, including cap, when handling the milk. 

Bottles must be capped, as soon as possible after filling, 
with the sterilized disks. 

II. Examination of the Milk, and Dairy Inspection. — 
In order that the dealer and the commission may be kept 
informed of the character of the milk, specimens taken at 
random will be examined weekly by experts for the com- 
mission of the department of health, the use of the labora- 
tories having been given for that purpose. 

The commission reserves to itself the right to make inspec- 
tions of certified farms at any time, and to take specimens of 
the milk for examination, and to impose fines for repeated or 
deliberate violations of the rec^uirements of the commission. 

The commission also reserves the right to change its 
standards in any reasonable manner upon due notice being 
given to the dealers. 

The expense of making the regular milk reports and the 
inspections are borne by the dealers. The treasurer of the 
Medical Society of the County of New York will send 
bills the first of each month for the certification for the pre- 
vious month. 

The monthly charges, which are intended to cover all 
expenses, are as follows: 

For daily output of less than 100 quarts $ 8 

For daily output of from 100 to 200 quarts 10 

For daily output of from 200 to 500 quarts 12 

For daily output of over 500 quarts 15 

Where the output of a farm is sent to several dealers, 
each dealer pays: 

For daily output of less than 100 quarts $ 6 

For daily outjjut of from 100 to 200 quarts 8 

For daily output of from 200 to 500 quarts 10 

For daily output of over 500 quarts 12 



64 DAIRY TECHNOLOGY 

The names of the dealers, with their addresses, are printed 
on cards, and enclosed with the monthly bulletin of the 
medical society, which is sent to about 1700 physicians. 
For this one dollar is charged each month. 

Details of the Workings of Various Commissions. — The 

maximum number of bacteria per cubic centimeter allowed 
in certified milk is, in the majority of cases, 10,000; how- 
ever, this factor varies with different commissions from 
5000 to 25,000 in winter and from 10,000 to 50,000 in 
summer. 

The per cent of fat in the certified milk may vary from 
3.25 to 5.5. Some commissions require the approximate 
per cent of fat to be stated on the bottle. Only about 
one-half the commissions have a standard for solids not 
fat, and in these cases it varies from 8 per cent to 9.3 per 
cent. 

All the commissions report little or no difficulty in keep- 
ing the milk up to the standard. 

The number of quarts of milk handled daily under cer- 
tification of one commission varies from 120 to 9373. 
The price for which this product is sold is from one to 
twelve cents per quart higher than the price paid for 
general market milk. 

New commissions are constantly being organized, and 
there is a steadily increasing demand for certified milk, 
but there is some scarcity of dairymen competent and 
willing to undertake the task of producing milk of such 
high grade. The price received for the product hardly 
pays for the great expense and care necessary to keep up 
to standard. 

Use of Certified Milk. — Certified milk will probably 
never displace the common market milk because it is of 
higher grade than is necessary for general consumption. 



CERTIFIED MILK 65 

But the value of this milk, for the feeding of infants and 
others whose digestive systems are not strong, is generally 
recognized. 

The greatest and probably the only objection to the use 
of certified milk is its greater cost, but this disadvantage 
is offset by the following advantages: 

1. Certified milk is free from pathogenic organisms. 

2. It is low in total bacteria and especially so in un- 

desirable species. 

3. The physical and chemical properties of the milk 

arc uniform from day to day. 

4. Cleanliness and cold are the only preservatives 

used. 

5. It is a safe food for any one. 

Production of Certified Milk. — A model dairy farm 
for the production of certified milk is equipped with a 
well lighted, well ventilated, tight barn, having few beams 
and braces to catch dust, a cement floor, mangers, and 
plastered walls, so that the whole place may be cleaned 
easily and Cjuickly each day. 

All cows are annually tested for tuberculosis, and any 
cow showing any indications of disease or abnormality of 
any kind is isolated and her milk rejected. The cows 
are daily curried or brushed, or cleaned with a vacuum 
cleaner; the hair on flank and udder is clipped short; 
and the greatest care taken to have the animal perfectly 
clean. Before milking, all cows are made to stand on 
their feet, and a chain is run under their necks along the 
stanchions to prevent them from h'ing down again before 
being milked; then the udder and flank are washed with 
clean warm water. 

No cleaning, brushing or disturbing of bedding and hay 



66 DAIRY TECHNOLOGY 

is permitted within an hour before milking time, so that 
the air may be free from dust when the milk is drawn. 

At milking time the milker, dressed in a clean white 
suit, approaches the cleaned cow with a steam-sterilized, 
covered milk pail, sits well back from the cow to avoid 
brushing her with his arms or head, and holds the pail at 
an angle to prevent dirt from dropping into the milk. 
The milker's hands are clean and he touches no part of 
the cow but her teats ; the fore milk is drawn into a separ- 
ate receptacle and discarded. 

Having completed the milking of one cow, the milker 
carries his pail to the milk room, hands it to the person 
in charge, who weighs the milk, wipes the top of the pail 
with a damp cloth and pours the milk over an enclosed 
cooler. During this time, the milker washes his hands 
and wipes them on a clean towel, then returns to milk 
another cow. 

In the milk room the milk is run over a cooler into sterile 
cans, then removed to the bottling room and put into 
sterile bottles, capped and packed in ice ready for de- 
livery. 

This milk reaches the consumer within less than 24 hours 
from the time it is drawn and at a temperature of 50° F. 
or less. 

Inspected Milk. 

Milk of this grade is general market milk produced on 
average farms, but subject to supervision of inspectors. 
This grade of milk is usually of sufficiently high quality for 
general use in the household. 



CHAPTER VII. 

PASTEURIZED MILK. 

Pasteurization of milk in the city milk plant is becom- 
ing very general, so that frequently the inspected and 
ordinary market milk are subjected to this process. In 
some instances this grade of milk wholly displaces the 
inspected milk. The advisability of adopting pasteuriza- 
tion instead of, and in addition to, close inspection as a 
means of improving our milk supply is a much-mooted 
question. 

The problem of quickly perfecting the milk supply of a 
city is a very difficult one. If stringent laws were enacted 
and immediately put into force (for example, a law pro- 
hibiting the sale of milk from dairies scoring under 80 per 
cent by the score card) there would be a milk famine in 
many cities. Hence it is evident that improvement at the 
place of production cannot be made in a day or a week; 
but when it does come, it will be a gradual evolution stim- 
ulated by education and public sentiment, and by paying 
the producer a higher price for his product. Therefore, 
quantities of milk produced under conditions of an un- 
known degree of sanitation must be admitted to the market. 
In order to improve the milk of doubtful character, it is 
recommended that all such milk be properly pasteurized. 
It is an undisputed fact that certified milk is better than 
pasteurized milk, but under existing conditions it is some- 
times necessary to choose between pasteurized milk and no 
milk. 

67 



68 DAIRY TECHNOLOGY 

Alleged Disadvantages of Pasteurization. 

Those opposed to the use of pasteurized milk for city 
milk supply, find the following objections to this product: 

1. It promotes carelessness and discourages efforts 

to produce clean milk. 

2. It produces chemical changes in the milk which 

render it less easily digested. 

3. Desirable lactic-acid bacteria are killed, while some 

undesirable types (spore formers) are not. 

4. Germs are killed, but their toxic by-products re- 

main. 

5. Pasteurization covers defects in milk. 

6. It affects flavor and creaming property. 

7. The cost of pasteurization is considerable. 

I. Promotes Carelessness. — It is claimed that pasteur- 
ization will encourage the producer and handler of milk to 
be careless and use unclean methods, believing great care 
unnecessary because the milk is going to be "cooked" any- 
way. The dealer may be careless in regard to the tempera- 
ture at which the pasteurized milk is held and permit the 
spores to vegetate and multiply to such an extent that 
the milk would be a very dangerous food. If pasteurized 
milk be placed in unclean bottles and the organisms be per- 
mitted to multiply, by keeping it too long a time, such milk 
probably would be more unhygienic than the raw product. 

In reply to this it may be said that pasteurization is a 
corrective measure and this is never as satisfactory as a 
preventive measure. In many cities milk is inspected by 
the health authorities before pasteurization, and if found 
to be very unsanitary is condemned. It is to the interest 
of the dealer to have milk in good condition before pasteuri- 
zation, because it insures a product having better flavor 



PASTEURIZED MILK 69 

and keeping qualities than that from unsanitary milk. 
Milk of doubtful sanitary qualities is an existing evil, and 
pasteurization is a present and efhcient remedy. 

2. Produces Chemical Changes in Milk. ^ The chemical 
changes wrought in milk by the heating process are said 
to render milk less digestible and to cause rickets and scurvy 
in children. 

The pasteurization of milk for adults, however, can be 
no more objectionable than the cooking of meat. It is 
steriHzation and high temperature pasteurization which 
cause changes in milk, while on the other hand, a tempera- 
ture of 145° F. for twenty minutes (as is commonly used 
in commercial pasteurization) does not appreciably affect 
its physical and chemical properties. 

Nature did not intend that milk should be cooked, neither 
did nature intend that milk should be exposed to bacterial 
contamination and unfavorable surroundings, and be al- 
lowed to undergo fermentative changes for a day or two 
before being consumed. 

An excessively high temperature, especially if prolonged, 
will, it is true, decompose some of the proteins, diminish 
the organic phosphorous, increase the inorganic phos- 
phorous, precipitate the calcium and magnesium salts and 
phosphates, expel most of the carbon dioxide, partially 
caramelize the lactose, cause a coalescence of some of the 
fat globules, and coagulate some of the serum albumin. 
Heat also destroys the enzymes which, according to some 
authors, aid in digestion and metabolism. 

3. Desirable Lactic-acid Bacteria are Killed, while 
Some Undesirable Types are not. — ■ Since lactic-acid 
organisms are not spore producers they have as low a 
thermal death point as the pathogenic organisms, and are 
killed by pasteurization. In raw milk the lactic-acid 



70 



DAIRY TECHNOLOGY 



bacteria inhibit the growth of the putrefactive organisms, 
but in pasteurized milk the spore-producing putrefactive 
bacteria have a clearer field for growth, and may develop 
poisonous substances without changing the appearance or 
physical condition of the milk. 

Ayers and Johnson^ have found that milk pasteurized 
under commercial conditions sours because of the develop- 
ment of lactic-acid bacteria which, on account of their 
high thermal death point, survive pasteurization; and per- 



idp|Valve 

n 



Milk Tank 




Pump 



ft 



REVOLVING SPIRAL HEATING COIL 




Water 
Tank 



Fig. 2. — Combination heating, holding, and cooling tank. 
(Circular 184, Dairy Division, U. S. Dept. of Agr.) 

haps, in some cases, because of subsequent infection with 
acid-forming bacteria, during cooling and bottling. The 
nature of the souring of efficiently pasteurized milk (140° 
F. for 30 minutes or 160° F. for a few seconds) is similar 
to that of clean raw milk. In both classes of milk, accord- 
ing to the same authorities, the alkali or inert bacteria 
constitute the largest group, the lactic acid next, and the 
peptonizers the smallest group. As these milks are held, 
the lactic-acid group gains ascendency over the other two 
classes, while the peptonizers remain the smallest group. 
1 U. S. Dept. of Agr., Bu. An. Ind., Bui. 126. 



PASTEURIZED MILK 7 1 

The cleaner the raw milk, the smaller is the percentage of 
lactic-acid bacteria. Also, the more efficient the pasteuriza- 
tion, the smaller is the percentage of lactic-acid organisms. 
The number of peptonizers, in a good grade of commercially 



tgji^?^ Outgoing Milk 

Fig. 3. — Holding tank with automatic emptying device. 
(Circular 184, Dairy Division, U. S. Dept. of Agr.) 

pasteurized milk, on the initial count and on succeeding 
days, is approximately the same as in a clean raw milk 
held at the same temperature. In milk heated for 30 
minutes at 140° F., it was found that about five per cent 
of the acid producers resisted the heating. 



72 



DAIRY TECHNOLOGY 



Hot 

I Pasteurized 

'Milk 



4. Toxic Properties Remain in Milk. — Many bacterial 
toxines are destroyed by heat, but others are not; hence it 

is argued that pasteurized 
milk may still be an un- 
wholesome product. 

The existence of toxines 
in market milk has been 
largely inferred, not dem- 
onstrated. If heat-resist- 
ing toxines exist in milk, 
the raw product will be 
just as toxic as the heated, 
and probably more so, be- 
cause heating would stop 
the development of the 
toxines. 

5. Pasteurization Covers 
Defects in Milk. — Pas- 
teurization may be used 
to hide the age of milk, 
so that the surplus from 
one day may be disposed 
of on the following day. 
By re-pasteurization, milk 
might be held for a long 
Fig. 4. — Sectional view of a regenerative ^ime without showing its 
cooler. (Circular 184, Dairv Division, i ,.^. 

TT c T^ 4- c A \ ' aged condition. 

U. b. Dept. of Agr.) ^ 

The re-pasteurization of 
milk, however, is prohibited by law in some cities. Such a 
practice is not conducive to securing a high-grade product and, 
so far as known, does not obtain under commercial conditions. 
6. AJ'ects Flavor and Creaming Property. — When milk 
has been subjected to a high temperature the cream rises 




Outlet for Cold 
Pasteurized Milk 



PASTEURIZED MILK 



73 



more slowly and less completely than it does in the case 
of unheated milk. The viscosity of the milk is lessened 
and the milk appears to have a lower fat content. Heated 
milk has a characteristic, so-called, cooked flavor, which 
is objectionable to many people. 

Although pasteurization inhibits cream from rising, 
the amount of cream in the milk is not decreased. When 
customers learn to know this fact, pasteurization is not 
so much objected to. As the process of pasteurization 



Supply; Tank 

Pasteurizer 




Fig. 5. — General arrangement of machinery for pasteurizing milk. 
(Circular 184, Dairy Division, U. S. Dept. of Agr.) 

is carried on under commercial conditions at the present 
time, the creaming property of the milk is affected but 
little, if at all, and no cooked flavor can be detected after 
the milk has been cooled and held a few hours. Some 
people prefer the flavor of heated milk to that of unheated. 

7. Cost of Pasteurization. — The cost of pasteurizing 
milk for city supply is difflcult to state. This would vary 
with the amount to be pasteurized, the kind of help, the 
method of pasteurization, the cfiiciency of boiler and other 
machinery, and the handiness of the plant. 

Generally speaking, i pound of steam heats 1000 pounds 



74 



DAIRY TECHNOLOGY 



or 500 quarts of milk 1° F. It is necessary to heat the 
milk about 100° F. 100 pounds of steam are then re- 
quired to heat 1000 pounds of milk 100° F. As i pound 
of coal produces about six pounds of steam, about seven- 
teen pounds of coal are necessary to pasteurize the 1000 
pounds of milk. The cost of this coal at $6.00 per ton, 
is about 5.1 cents. It costs an equal amount, 5.1 cents, 
to bring the temperature of the boiler up to the point of 




Fig. 6. — View of C. P. pasteurizing machiine. 



steam pressure. The cost of cooling this amount of milk 
may be estimated at 50 cents. If the pasteurizing ma- 
chinery costs $2000 the depreciation of same may be 
estimated at $1 per day; thus the machinery should last 
10 years. The interest at 7 per cent amounts to about 
forty cents per day. In addition it costs $1.50 for one- 
half day's labor. The total cost of pasteurizing 500 quarts 
of milk 100° F. is then about $3.50 per day, or 0.7 cent 
per quart. 



PASTEURIZED MILK 



75 



Advantages of Pasteurization. 

The following arguments are presented in favor of the 
use of pasteurized milk; 

1. Protection from pathogenic bacteria occasionally 

found in milk. 

2. A decrease in the total number of bacteria. 

3. Aids in the preservation of milk. 

1. Protection from Pathogenic Bacteria. — Epidemics, 
such as typhoid fever, diphtheria and scarlet fever, are 
on record as having been transmitted through milk, as 
has already been mentioned in Chapter IV. Several in- 
vestigations of market milk have revealed the presence 
of the tubercle bacillus in approximately 10 per cent of 
the dairies. There is strong evidence showing that these 
diseases, under certain conditions, may be transmitted 
to the consumer. This danger may be obviated and the 
pubhc protected by efficient pasteurization of the entire 
city milk supply. All of these pathogenic germs are 
destroyed by pasteurization, as they are not spore forming. 

2. Decreases the Total Number of Bacteria. — Milk as 
a food is of greatest importance to the welfare of chil- 
dren, and the decrease of infant mortaHty is one of the 
virtues claimed for pasteurized milk. 

We have already seen in a previous chapter how the 
Nathan Straus milk depots alleviated infantile gastro-mesen- 
teric illness, and how the installation of a pasteurizing plant 
at the Children's Home on Randall Island, New York City, 
decreased the annual death rate. Many similar instances 
of the benefits of milk pasteurization may be mentioned. 

Variot distributed for 12 years in the poorest cjuarters 
of Paris about 400,000 bottles of pasteurized milk to more 
than 3000 infants, and reports that there was never a single 



76 DAIRY TECHNOLOGY 

case of scurvy or rachitis among the consumers of the 
milk, and that the infants maintained their heaUh and 
normal development on this diet. 

Park & Holth of New York City found (1902-1903) 
that infants fed on pasteurized milk thrived much better 
than those fed on raw milk. They experimented on 50 
babies from the tenement houses, and divided them into 
two equal lots. They were all fed on milk modified at the 
Straus milk depot. They were treated the same, excepting 
one lot, who were fed milk pasteurized 30 minutes at 
165° F., and the other half were fed the same kind of milk 
unheated. The pasteurized milk in the morning con- 
tained 1000 germs per cubic centimeter, while the raw 
milk contained 1,200,000 per cubic centimeter, and the 
pasteurized milk contained in the afternoon of the same day 
50,000 germs per cubic centimeter while the raw milk 
contained 20,000,000 per cubic centimeter. 

The investigators made the following remarks: 

" Within I week, 20 of the 27 infants put on the raw milk, 
suffered from moderate or severe diarrhea, while during 
the same time, only 5 cases of moderate and none of 
severe diarrhea, occurred in those taking pasteurized milk. 
Within a month, 8 of the 27 had to be changed from raw, 
back to heated milk, because of their continued illness. 7, 
or 25 percent, did well all summer on raw milk. On the 
other hand, of those receiving the pasteurized milk, 75 per- 
cent remained well or nearly so all summer, while 25 per- 
cent had one or more attacks of severe diarrhea. There 
were no deaths in either group of cases." 

Berlioz, in Grenoble, France, distributed from 1894 to 
1897 sterilized milk (heated under pressure) for infant feed- 
ing, and found an average death rate of 27.9 per 1000 for 
those using the sterile product, as compared with a death 
rate of 69.3 per 1000 for infants fed on raw milk. 



PASTEURIZED MILK 77 

3. Pasteurized Milk Keeps Longer. — Milk is com- 
monly bought in quantities sufficiently large to supply the 
consumer for 24 hours. During hot weather, even a good 
quaUty of inspected milk may become unfit for use in 
24 hours, unless a very low temperature is maintained. 
Among the poorer classes and even among the middle 
classes, ice is too expensive to use for cooling purposes. 
But because of the improved keeping qualities of pasteu- 
rized milk, the consumer is able to keep this grade of milk 
in a hygienic condition for a longer time than the regular, 
inspected raw milk can be kept. 

Because of the prolonged keeping quality, the dealer 
has fewer complaints from his customers, and he has 
less loss through the souring of milk before it can be 
delivered. Hence pasteurization is of economic import- 
ance. 

Pasteurization of Milk Increasing. — That pasteuriza- 
tion is being adopted by more and more cities and dealers, 
speaks strongly in favor of this grade of milk. In the year 
1900, only 5 per cent of New York City's milk supply was 
pasteurized; in 1909, 25 per cent was pasteurized, and 
probably t^t^ per cent now undergoes heating. The city 
board of health has ruled that after January i, 191 2, all 
milk, except that produced under certain conditions, shall 
be pasteurized. In Boston 33 per cent of the milk is pas- 
teurized; in Chicago 50 per cent, and in Milwaukee about 
seventy-five per cent. 

Official Supervision of Pasteurization. — H. C. CampbelP 
has shown that, in cities where milk pasteurization is not 
under official supervision, commercial pasteurization can- 
not be relied upon as a means of destroying pathogenic 
bacteria in milk. 

^ U. S. Dept. of Agr., Bu. An. Ind., An. RcpL, 1909. 



78 DAIRY TECHNOLOGY 

Russell and Hastings/ Schroeder^ and others have shown 
that a temperature of 140° F., for 20 minutes, is sufficient 
to kill tubercle bacilli in milk. Schroeder tells us that: 

" The simplest, the least expensive, and the most effi- 
cient available expedient through which the public can be 
protected against bovine tubercle bacilli and other viruses 
that may be disseminated with milk is pasteurization." 

He also states that, until commercial pasteurization has 
been placed under official supervision, home pasteurization 
should be employed as the best solution to the milk problem. 

Inefficiency of pasteurization under commercial con- 
ditions is usually due to ignorance or carelessness. The de- 
gree of heat and the time of exposure that are necessary to 
improve the keeping quality of milk also kill all pathogenic 
organisms. The finding of contagious disease producing 
germs in milk is an indication that the dealer has not even 
accomplished his special object of improving the keeping 
properties of his milk. The dealers, as well as the patrons, 
suffer because of this lack of efficient pasteurization. 

The movement for the adoption of compulsory official 
supervision of all milk for city supply is gathering momen- 
tum and producing most satisfactory results. In cities 
where such supervision is properly enforced, the pasteurized 
milk can be relied upon. 

Laws and Ordinances Pertaining to Pasteurization. — 
There has been, during the past few years, considerable 
legislation pertaining to pasteurization. New York City 
has recently added the following rules to its sanitary code: 

I. Pasteurization must be carried out under a permit 
therefor issued by the board of health, in addition to the 
usual permit for milk. 

^ Outlines of Dairy Bacteriology. 

2 U. S. Dept. of Agr., Bu. An. Ind., An. Kept., 1909. 



PASTEURIZED MILK 79 

2. Only such milk or cream shall be regarded as pasteur- 
ized as has been subjected to a process in which the tem- 
perature and exposure conform to one of the following: 

No less than 158 degrees F. for at least 3 minutes. 
No less than 155 degrees F. for at least 5 minutes. 
No less than 152 degrees F. for at least 10 minutes. 
No less than 148 degrees F. for at least 15 minutes. 
No less than 145 degrees F. for at least 18 minutes. 
No less than 140 degrees F. for at least 20 minutes. 

3. The milk after pasteurization must be at once cooled 
and placed in sterile containers and the containers sealed. 

4. All pasteurized milk must be dehvered to the con- 
sumer in sealed containers which are plainly labeled, 
" Pasteurized." The label must also bear the date and 
hour when the pasteurization of the milk was completed, 
the degree of the heat employed, the length of time exposed 
to the heat and the number of the pasteurization permit 
issued by the board of health. 

5. Pasteurized milk must be delivered to the consumer 
within 24 hours of the pasteurization. 

6. No milk shall be pasteurized a second time. 

Home Pasteurization. — Milk may be efficiently pas- 
teurized in the home, if the person doing the work has a 
thorough knowledge of the process. It is not safe, how- 
eve, to leave it to irresponsible servants. 

The bottle of milk as it is received from the delivery- 
man may be immersed in water (not hot enough to break 
the bottle) to its neck in a cooking vessel. The milk should 
first be well shaken to insure uniform heating. If thick 
cream be left on top of the milk, it will not circulate well 
and will not be so quickly nor efiiciently heated. A dairy 
thermometer may be stuck through the pulp cap, the vessel 
set upon the stove and the milk heated to the necessary 
temperature. The milk may be cooled slowly in this vessel 
by occasionally adding a small quantity of cold water 
until the milk is cooled to the temperature of the water. 



CHAPTER VIII. 

MODIFIED MILK. 

Use of Modified Milk. — The normal healthy adult 
does not need this class of milk. But the ability of the 
infant, the invalid, and persons suffering from indigestion, 
is at times such that normal milk may not be properly 
digested and assimilated. Hence, it becomes necessary 
to modify this natural product to meet the requirements 
of these individuals. 

Although the quantity of this grade of milk consumed, 
like certified milk, is very small compared with the great 
bulk of regular market milk, it is of great importance, 
because of its extensive use for infants. 

Digestibility of Modified Milk. — The modification of 
milk for infant feeding owes its origin and present use to 
the fact that normal cow's milk frequently cannot be 
properly digested by an infant. This is due, first, to 
cows' milk having a different composition from that of 
human milk; and, secondly, to the fact that some infants 
have weak digestive systems and therefore require milk 
of special composition. Therefore, it becomes necessary 
so to alter the composition and the physical and chemical 
properties of the milk that it may be properly digested 
and assimilated. 

It is possible that the casein in cows' milk is too often 
held to be responsible for digestive troubles in infants, 

Huebner,^ Keller and Czerny in Europe, and Brenne- 

^ Hygienic Laboratory, Bui. 56. 
80 



MODIFIED MILK 8l 

mann^ and Walls in this country have shown that, in itself, 
cows' milk proteid is almost as easily digested by infants 
as is that of human milk. Czerny and Keller have shown 
that it is the fat, not the proteid, that is the main cause of 
digestive disturbances. 

Since there are so many infants that, for various reasons, 
are artificially fed, the proper modification of milk to 
meet their needs is a very delicate and important matter. 
The milk provided by nature for the infant is usually the 
best food; hence, in artificial feeding, the aim is to imi- 
tate this product as closely as possible. It is therefore 
necessary to have an exact knowledge of the composition 
and characteristics of human milk. 

Human Milk. — The first few days after parturition, 
colostrum is secreted as in the case of lower animals. This 
is characterized by a higher proteid and mineral content, 
and a lower fat and sugar content than the normal milk, 
and in addition contains numerous colostrum corpuscles, 
which are four to five times as large as the normal fat 
globules. 

The composition of human colostrum milk, according to 
Pfeiffer, is 

_ Proteid 5.71 

Fat 2 . 04 

Sugar 3.74 

Salts or minerals 0.25 

Water 88.23 

Normal Human Milk Compared with Cows' Milk. — 

The composition of human milk has not been very 
thoroughly investigated, but an average of the most recent 
analyses by some of our best authorities is shown in the 

^ Hygienic Laboratory, Bitl. 56. 



82 



DAIRY TECHNOLOGY 



following table, together with the average composition of 
cows' milk. 



Human. 



Cow. 



Fat 

Proteid 

Sugar 

Salts (ash) , 

Water 

Calories per kilogram (or 2.2 lbs.) 



4.00 


3-5° 


1-50 


4.00 


7.00 


4 -SO 


0.20 


0.7s 


87-30 


87-25 


100.00 


100.00 


710.50 


726.00 



It may be noted in the table that the main difference 
in the composition of the two milks is that human milk 
is lower in proteids and ash and higher in sugar than is 
cows' milk. 

According to Koenig, the proportion of lactalbumin 
to casein is as 5 to 4 in human milk. This is a marked 
variation from the proportion of these constituents in 
cows' milk, which latter is about one to three. 

When dilute acids are added to normal human milk a 
light flocculent precipitate is formed instead of the solid 
curd formed in cows' milk. Rennet extract, although it 
quickly coagulates cows' milk (when under proper con- 
ditions) does not materially affect human milk. 

Food Requirements of Infants. — The diet of adult 
man has been a subject of study for many years, but the 
nutritive requirements of infants have received detailed 
and thorough attention only during the past few years. 
0. Heubner^ of Berlin was, so far as known, the first in- 
vestigator along this line, but he now has many followers.^ 

^ Heubner — Die Energiebilanz des Sauglings. Zeitschrift f. diate u. 
physik. Theraouem, 1901. Vol. V. — Reviewed in Hygienic Lab. Bui. 56. 
2 Bren and Walls — Am. Journal Med. Ass'n., 1907, Vol. XL VIII. 



MODIFIED MILK 83 

He calculated the bodily needs of the infant on the calorie 
basis, and finds the following daily requirements per 
kilogram (about 2.2 pounds) of body weight: First week 
in hfe, 60 calories (i calorie being the amount of heat 
required to raise i kilogram of water 1° C); first 3 months, 
100 calories; second 3 months, 100 to 90 calories; third 
and fourth 3 months, 80 calories per kilogram of body 
weight per day. The maximum and minimum requiro- 
ments being 100 to 70 calories respectively, when these 
limits were overstepped unfavorable results ensued. 

In addition to the required heat units, the infants' food 
must contain the proper proportion of the various classes 
of nutrients — proteid, carbohydrates and fat, and min- 
eral matter. The proper ratio of the different constituents 
will vary, depending upon the following conditions: in- 
dividuality, age, activity of the infant, amount of fresh 
air received and other general conditions of living. 

Manner of Modifying Milk. — The milk prescribed 
shall be of such quality and quantity (above-named con- 
ditions considered) as to furnish the energy quotients re- 
quired, and no more, and, at the same time, contain the 
proper proportionate amount of each of the different food 
nutrients. 

To calculate the number of calories in the modified 
milk the following figures may be used: 

I gram of butter fat produces 9.3 calories. 

I gram of proteid produces 4.1 calories. 

I gram of carbohydrate produces 4.1 calories. 

To insure the proper proportionate amounts of the 
different nutrients and make the modified milk resemble 
in composition human milk, it is necessary to reduce the 
amount of casein in cows' milk, increase the amount of 



84 



DAIRY TECHNOLOGY 



sugar, and still maintain the other constituents at normal. 
This may be done by mixing, in the proper proportion, 
liquids of known composition, for example, cream, whey 
(containing added milk sugar) and distilled water as 
follows : 

To make lOo pounds modified milk: 



20 lbs. cream (18 per 
cent fat) 

70 lbs. whey (8.5 per 
cent milk sugar) 

10 lbs. distilled water.. 

100 lbs. containing. . . . 



Fat. 


Casein. 


Albumin. 


Sugar. 


Lbs. 


Lb. 


Lb. 


Lbs. 


3.60 


0.50 


0-I5 


1. 00 


0.14 


0.03 


0.49 


5-95 


0.00 


0.00 


0.00 


0.00 


3-74 


0-53 


0.64 


6.9s 



Ash. 



Lb. 

o. 14 

0.49 
0.00 
0.63 



The composition of this modified milk approaches, 
very closely, that of human milk. 

In large cities there are special laboratories in which 
modified milk is prepared. Calculated tables are con- 
sulted, so that any quantity of fresh modified milk can 
quickly be made. The physician prescribes milk of a 
certain composition. This prescription can then be taken 
to the laboratory, and the modified milk is put up in ac- 
cordance with the prescription. This milk is put into 
small bottles containing only one feed. The Walker 
Gordon laboratories are in operation in many of the large 
cities in the United States, and do a large volume of 
business along this line. 

Homogenized Milk.^ — This class of milk is found on 
the markets of this country only in very rare instances, 
though it is used to some extent in European countries. 

Homogenized milk seems to be objected to in this coun- 



^ The homogenizing machine and the use of homogenized cream for ice- 
cream making are described in Chapter XIX. 



MODIFIED MILK 



85 



try. In the first place, there is a wide practice of using 
the cream from the top of the bottle for coffee or other 
special purposes. This cannot be done when homogen- 
ized milk is used, because there is no apparent cream 
on homogenized milk. 




Fig. 7. — The Gaulin homogenizer. 



The consumer commonly judges the richness of milk 
by the amount of cream that can be seen at the top of the 
bottle. By this standard homogenized milk does not show 
up well. 

However, in all cases where it is desirable to use whole 



86 DAIRY TECHNOLOGY 

milk the homogenized milk is preferable to natural milk, 
because the former is always ready to use without mixing, 
and the cream never forms in hard lumps as is sometimes 
the case when natural milk stands for a long period. The 
fat globules of homogenized milk are very minute, which 
condition makes them more easily digested. It is also 
claimed that the homogenization process destroys many 
bacteria, and therefore homogenized milk has better 
keeping properties. This latter, however, has not been 
thoroughly investigated. 



CHAPTER IX. 

[THE VILLAGE MILK PLANT. 

The milk supply of a farm community is not so vital 
a problem for consideration by the general public, because 
the consumer, as a rule, is his own producer. The con- 
sumer uses the quality of milk that he produces, and if 
he does not have a pure and sanitary milk for use, no one 
but himself is to blame. 

In the small city or village, conditions are but one step 
more complex than this. The consumer is supplied with 
milk by his neighbor, who generally resides just outside 
of the village limits. The city milk dealer and the pro- 
ducer are, as a rule, one and the same person. The milk 
produced in the morning, together with that of the pre- 
vious night, is delivered to the consumer the same morn- 
ing by the dairyman who produced it. This milk usually 
is exposed to less contamination, and is kept for a shorter 
time before delivery than the ordinary market milk of 
a large city. But from a sanitary point of view there is 
wide latitude in the operation of small city milk plants. 

Objectionable Practices. — The small city milk plant, 
operating on but a small scale, cannot afford an elaborate 
and expensive equipment. In many places hot water 
and steam for cleaning purposes are available only in 
limited supply, which results in less thorough cleaning 
of bottles and utensils. 

A number of practices that some small milk dealers 
follow should be condem.ned. Among these are, first, 

87 



88 



DAIRY TECHNOLOGY 



the selling of " loose milk," that is, dipping out from a 
supply can the amount desired by the purchaser, and 
placing it in a pan or other receptable; second, omitting 
to wash and sterilize returned bottles merely because 




Fig. 8. — The Bestov milk-cooler. 



they appear to be clean or allowing careless cleaning 
in the milk plant, the milk bottles when refilled without 
being washed may be the means of spreading disease; 
third, filling the bottles on the street. 

A dairy of forty or more cows should afford a well- 



THE VILLAGE MILK PLANT 



8g 



equipped milk house; and, since cleanliness is the most 
important consideration, the factors of prime importance 
in the milk house are sanitary construction and a small 
upright boiler to furnish an abundant supply of hot water 
or steam for cleansing and sterilizing. 



Equipment of the Plant. 

The equipment of a small dairy may vary between 
wide limits, depending upon size, prosperity, grade of 
milk produced, and the individuality of the owner. 

Cooling the Milk. — The milk may be cooled by settmg 
the cans in a tank of water, or an expensive cooling appara- 
tus may be used. Between these extremes are numerous 
coolers adaptable to all conditions. 
Whatever method of cooling is em- 
ployed, it is extremely important that 
the milk be cooled at once after it has 
been drawn from the cow. 

Bottling. — Bottles may be filled by 
pouring from a pitcher or spouted can, 
or a modern bottle -fiinng machine may 
be used. Many small dairymen use a 
large can similar to a small weigh can, 
but having one or two small faucets, 
under which bottles are placed for fil- 
ling. Superior to this, but more costly, 
is the filler with the automatic cut-off 
valve, that insures having the bottles 
filled to the right point and prevents 
overflowing. When bottles are filled 
in this way there is no milk spilled on the outside of the 
bottle. The bottle is filled to such a point that the cap 
may be placed upon it without dipping it into the milk. 




Fig. 9. — Circular disk 
milk cooler. 



go 



DAIRY TECHNOLOGY 



Capping bottles that are over full causes the excess of milk 
to squirt out on to the dairyman's hands and to drip from 




Fig. io. — Quaker City milk-filler. 



there to other caps and into other bottles. This is not 
sanitary. 

In a report of the " Association for Improvement of the 
Milk Supply of New York City " is given the bacterial 



THE VILLAGE MILK PLANT 



91 



content of milk bottled and capped by hand and that of 
milk bottled and capped by machine. The average of 
three samples of each class of milk is as follows: Bottled 
by hand, 19,800 bacteria per cubic centimeter; bottled 
by machine, 6266 bacteria per cubic centimeter. 





Fig. 



II. — Davis hand 
bottle filler. 



Fig. 12. — Davis hand 
bottle capper. 



Capping the bottles by hand, although a very common 
practice, is not so sanitary as using a machine, neither is 
it so rapid. Caps for machine use may be bought. These 
are packed in paper tubes direct from the machine which 
makes the caps. These tubes are sealed so that the caps 
are not exposed to dirt and dust. Where bulk caps are 
used, they may be loaded into the metal tubes that are 



92 



DAIRY TECHNOLOGY 



furnished with capping machines and steriHzed. The 
simplest machine of this character is the single bottle 
capper, though, in a moderately large dairy, the combined 
filler and capper is found more economical in point of 
time. 

Bottle Washing. — Many small dairymen object to the 
expenditure necessary to secure a bottle-washing outfit, 




Fig. 13. — Turbine bottle washer. 



but the time saved and the better results secured by a 
washer will soon pay for one. The machine best adapted 
to the small dairy is a brush revolved by a steam turbine 
or by a water motor, combined with suitable sinks and 
rinsing apparatus. 

The small dairy that is equipped with a steam boiler to 



THE VILLAGE MILK PLANT 93 

supply plenty of hot water for washing should have no 
difficulty in getting the bottles and cans almost sterile. 

A sterile oven is a great addition to a dairy room, though 
a rather costly one. It is recommended for dairies pro- 
ducing a high grade of sanitary milk. 



CHAPTER X. 

THE CITY MILK PLANT. 

The large milk plant of a great city requires extensive 
equipment and a large building, and hence calls for con- 
siderable capital as well as knowledge of the dairy business. 

The milk is practically all received by rail, so that it 
is subjected to more possibilities of contamination than 
that of the village milk dealer. Generally the milk 
passes through the hands of at least three different persons 
or companies — the farmer or producer, the transportation 
company and the city milk company. 

Transportation. — Milk may be transported from the 
place of production to the market by steam or electric 
roads, boats or wagons. 

In practically all small cities, the wagon carries most of 
the milk from the farm to the consumer. And even in some 
very large cities this mode of transportation is employed 
to a great extent. We find that in Washington, D. C; 
Detroit, Mich.; San Francisco, Cal., and St. Louis, Mo., 
about half of the milk supply of the city comes in on wagons; 
while in Milwaukee, Wis.; Cincinnati, Ohio, and New 
Orleans, La., wagons bring about three-fourths of the milk. 
But in the larger cities, such as New York, Chicago and 
Philadelphia, about nine-tenths of the milk is brought in 
by steam and electric cars. 

Most of the milk that is shipped less than loo miles is 
carried in baggage or express cars attached to local pas- 
senger trains. But for greater distances special refrigerator 

94 



THE CITY MILK PLANT 95 

cars are commonly used. This depends upon the time 
of year and the weather conditions. For milk cars, some 
roads employ a modified baggage car equipped with racks 
along the side for holding ice. A better milk car is used 
by one of the roads carrying milk to New York City. It 
is a refrigerator car with a capacity of 325 eight-gallon 
cans, having an ice compartment at each end, so that milk 
may be kept at a temperature of 50° F. Every day the 
cars are scrubbed and thoroughly cleaned. 

Another road has refrigerator milk cars with asbestos- 
lined walls, sheet-steel floors and regular refrigerator doors 
and an ice capacity of 500 pounds at each end of the car. 

The careful dairyman delivers his well-cooled milk at 
the station a short time before the arrival of the car or 
boat, but right here is a possibility of spoiling milk. Milk 
stations are often merely open platforms with no roof or 
other protection for the cans from the sun and heat in sum- 
mer. Milk will quickly warm to the danger point if left on 
such a platform. And as delayed trains are not an unusual 
thing, the souring of milk while in the hands of the trans- 
portation company is not an infrequent occurrence. In 
the older dairy districts we find milk stations with proper 
protection for the milk while it awaits the arrival of the 
train. 

Until very recent years, milk was brought from a dis- 
tance by steam cars or by boat, but the electric railway is 
now a keen competitor for the hauling of milk and has 
some advantages over the other methods of transportation. 
The electric lines penetrate the rural communities to a 
greater extent than do the steam roads, so that the farmer 
has the milk station closer to his door. The electric lines 
can carry their loads of milk to the center of the city, or 
to the milk plant itself, instead of dumping it all at one 



96 



DAIRY TECHNOLOGY 



great depot, located, perhaps, more than a mile from the 
milk plant, as is done, necessarily, by the steam road. 
Los Angeles has satisfactorily developed the milk traflfic in 
this way. 

Under present conditions, in most cities, milk is hauled 
by dray from the railway station to the city milk plant. 
This extra handling and labor cannot wholly be done away 
with. 

The Intake. — On arrival at the city milk plant each 
can must be inspected by an experienced man with a keen 




Fig. 14. — A-F gravity conveyers installed in Howell 
Condensed Milk and Cream Co. plant. 

sense of smell. Milk containing any sour or other un- 
desirable odor is not, and should not be, accepted. The 
inspection of milk on a large scale is done almost entirely 
by the sense of smell, because the sense of taste cannot be 
relied upon after several hundred cans of milk have been 
tasted in quick succession. 

However, there are other tests for the sanitary condi- 
tion of milk which are very useful under certain conditions, 
but are not being extensively used in this country at the 
present time, (See Chapter XII.) 



THE CITY MILK PLANT 



97 



The cans, when empty, may be turned up on a drip- 
saver, which, as the name indicates, saves whatever milk 
may drip out from the cans. Just beyond the drip-saver 
is the can washer. The cans are taken from the drip-saver, 
washed, steamed, and taken out by another door to the 
dray, which hauls them back to the railway station to be 
returned to the shipper. 

Sanitary Piping. — Having passed the inspector, the milk 
is emptied into a receiving vat, from which it is pumped 
into a storage tank that feeds 
the pasteurizer. This necessi- 
tates passing the milk through 
considerable piping as well as 
a pump. Needless to say, the 
pumps should be of the sani- 
tary type, so that they may be 
taken apart and thoroughly 
cleaned after each using. The 
piping must be the so-called 
sanitary piping, being tinned 
throughout, having a perfectly 
smooth interior, and in short 
lengths joined by couplings eas- 
ily taken apart with a spanner 
wrench. These pipes should be 
washed daily by rinsing with 
cold water, then pumping hot 

washing powder solution through them and finally rinsing 
with plenty of boiling hot water. 

However, they should be taken apart and thoroughly 
cleaned with a brush and sterilized at least once each week. 

Clarifying. — The presence of dirt or sediment of any 
kind in milk is strenuously objected to by the consumer. 




Fig. 15. — The Victor 
can washer. 



98 DAIRY TECHNOLOGY 

For this reason, some filter and clarify the milk. Milk 
filters have not given much satisfaction and are not used 
to any considerable extent. But the clarifying of milk 
by centrifugal force is being adopted to a large extent by 
city milk plants. Some of them use an ordinary cream 
separator and run the cream and skim milk together. At 
times the milk is standardized to the desired percentage of 
fat. 

The milk clarifier is a modification of the cream separa- 
tor, providing a greater capacity for the deposit of sedi- 
ment and delivering the whole milk from the machine 
instead of separating it. Removing dirt from milk re- 
moves some bacteria, leucocytes, etc., so that the clarified 
milk is a purer and cleaner food. 

Pasteurization and Cooling. — The large city milk plant 
commonly pasteurizes the milk, and for this purpose an 
intermittent pasteurizer or a continuous machine with a 
retarder is used, usually the latter. The milk is heated to 
from 140° to 160° F. and held at that temperature for from 
15 to 30 minutes, when it is discharged and conducted to 
the cooler. This latter is very commonly a vertical coil 
of pipes over which the milk flows in very thin sheets, 
while at the same time cold water or brine is flowing through 
the interior of the pipes, entering at the bottom and flow- 
ing out at the top. 

The pasteurization of milk, to be successful from a 
commercial standpoint, must be so carried on that the 
keeping qualities of the milk will be improved without 
heating to such an extent as to impart a cooked flavor or 
materially to injure the creaming qualities of the milk. 
It is a well-known fact among dairymen, that excessive 
heating and stirring of milk breaks the clusters of fat 
globules and scatters them throughout the serum. This 



THE CITY MILK PLANT 



99 




Fig. i6. — The l)e Laval centrifugal clarifier. 



lOO DAIRY TECHNOLOGY 

makes creaming very difficult, because the small globules 
are unable to overcome the viscosity of the milk serum. 
In unheated milk the fat globules are well clustered, and 
present a relatively small surface as compared with their 
volume. The creaming of milk is but slightly affected by 
temperatures up to 150° F., but subjecting it to a tempera- 
ture of 160° F. for 20 minutes retards it very markedly. 

Pasteurizers. — The pasteurization of milk may be 
accomplished by heating at a low temperature for a long 
time or at a high temperature for a short time. One 
class of machines, known as the intermittent or batch 
pasteurizer, is so operated that the milk may be heated 
at any temperature for any desired length of time. These 
machines are commonly vats or other receptacles in which 
the milk is heated and agitated mechanically. Cooling 
is accomplished by passing cold water through the agita- 
tor or jacket as the case may be. These machines are 
very efficient, but it can readily be seen that their capacity 
is limited, and hence they are hardly practicable except 
in a small business. 

The other class of pasteurizers is known as the con- 
tinuous or flask machine, because there is a continuous 
flow of milk through the machine and it is heated instan- 
taneously. The milk is heated to a high temperature and 
immediately passed on to the cooler. However, it has 
been shown by experiment, that all the milk is not heated 
to the same temperature, and hence some of it will not 
be thoroughly pasteurized and some of it will be over- 
pasteurized. 

A test^ of one of the commonly used machines revealed 
the fact that some of the milk passed through in 15 seconds, 
most of it was held 30 seconds and some of it 60 seconds. 

1 Russel and Hastings — Outlines of Dairy Bacteriology. 



THE CITY MILK PLANT lOI 

It is evident that a temperature sufficiently high to kill 
the bacteria in the milk that passed through in 15 seconds 
would cause undesirable effects on the milk that was 
exposed for 60 seconds. And if the temperature was 
regulated on the basis of an exposure of from 30 to 60 
seconds, it is evident that the milk passing through in 15 
seconds would be inefficiently pasteurized. 

The necessity of a continuous pasteurizer and the faults 
of the first machines led to the adoption of " holding " 
devices or " retarders. " In such machines the milk 
is passed through a continuous pasteurizer into a holding 
tank in which it is kept at the desired temperature for 
the desired length of time, then passed on to the cooler. 
Thus the good qualities of the two classes of pasteurizers 
are combined in one. These machines may be equipped 
with a thermo-regulator which automatically regulates 
the flow of steam to the pasteurizer and insures a uniform 
heating of the milk. In connection with this a recording 
device is commonly used, 20 that the slight variations in 
temperature are recorded. 

Pasteurization applied to fresh, clean milk, and to old, 
impure milk may destroy 99 per cent of the bacteria in 
both cases. Now it is quite evident that the clean milk 
before and after pasteurization would contain by far the 
smaller number of bacteria, and hence would have the 
better keeping qualities and be more healthful. 

Immediate cooling to about 40"^ F. subsequent to heat- 
ing is necessary for successful pasteurization; also all 
contamination after pasteurization must be guarded 
against. 

Pasteurization in the Bottle. — Another method of 
pasteurizing milk that has been introduced recently is 
pasteurization in the bottles. This method necessitates 



I02 



DAIRY TECHNOLOGY 



the use of a perfectly tight cap, one that will withstand 
the action of hot water and steam. Breweries have used 
such a method of pasteurizing their bottled beer for a 
number of years, while the dairy industry has but recently 
adapted it to bottled milk. 

One of the objections to the commercially pasteurized 
milk of to-day is that, although the pasteurization may 
have been efficient, contamination during the cooling. 




Fig. 17. — A type of beer-pasteurizing machine adaptable to the pasteuri- 
zation of milk in bottles. (Circular 184, U. S. Dairy Division.) 

bottling and capping processes is inevitable, and this 
contamination may be of a very serious nature. Pas- 
teurization in the bottle prevents such contamination 
and insures a safer product. 

Pasteurization of bottled milk is carried on to a limited 
extent in steam sterilizers, but a more efficient process 
is by the use of water. In the brewery there are two 
general classes of these pasteurizers. In one type the 



THE CITY MILK PLANT 



103 



bottles are placed in baskets, which are carried on an 
endless chain into tanks of water having different tem- 
peratures. In this way the bottles are passed through 
lukewann water, then through warmer and warmer water, 
until they reach the pasteurizing temperature. They re- 
main at this temperature for 20 minutes or any desired 
time; then they pass through a series of coohng tanks, 
each successive tank containing cooler water than the 
previous one. 

In the other t^pe of machine, the bottles are placed 
in trays on a large wheel revolving horizontally, where 
they receive a hea\y shower bath of water. As the wheel 
revolves the bottles pass through water of different tem- 
peratures just as in the above-described system, so that 
pasteurization and cooling are accomplished by a con- 
tinuous process. 

Mr. Bixby ^ of Boston compared pasteurization in a 
machine with pasteurization in bottles and secured the 
following results: 

NUMBER OF BACTERIA IN ONE CUBIC CENTIMETER 
OF MILK. 



Raw. 


Pasteurized in 
machine. 


Pasteurized in 
bottles. 


2,000,000 


99,000 


30,000 


2,000,000 


102,000 


34,000 


6,300,000 


42,000 


6,600 


1,960,000 


70,000 


1,200 


6,200,000 


65,000 


4,000 


2,100,000 


65,000 


8,100 



In both these methods of pasteurization, the same 
degree of heat and same time of exposure were employed. 

^ Medical Record. — July 15, 191 1. 



I04 



DAIRY TECHNOLOGY 



It is very evident from these figures that heating in the 
bottles gives by far the better results. 

In a similar experiment carried on by Dr. Charles E. 
North, New York, pasteurization in bottles reduced the 
bacterial content of the milk from about 500,000 to 500 




Fig. 18. — The Davis bottle filler and capper. 

per cubic centimeter. This was accomphshed without 
affecting the flavor or creaming of the milk. 

Bottling. — After pasteurization and cooling, the milk 
may be conducted to a storage tank of glass-enameled 
iron located in a cold room. It is now ready to be bottled. 
For filling and capping bottles, on a large scale, an auto- 
matic, power-driven machine is commonly used. It 
may be run by an electric motor so that a movement of 
a lever causes a case of bottles to be filled and capped. 
The labor required to operate such a machine consists of 
one man to feed in the cases of empty bottles, and one man 
to take the filled bottles from the machine. If gravity 
conveyers are used, the man who takes the cases of filled 



THE CITY MILK PLANT 



105 



bottles from the filler may place them on a conveyer 
which conducts them to a cold room for storage until 
called for by the delivery wagon. 

Delivering. — Cases of filled bottles are usually hauled 
to the loading platform on hand trucks, and frequently 
have to be taken to the floor above on an elevator. A 
system more economical, in the use of time and labor, is 




Fig. ig. — Davis Standard 12 bottle filler. 



that of the gravity conveyer and automatic elevator, by 
means of which filled cases may be taken to the platform 
as fast as they can be loaded into the wagons. 

Cases of empty bottles are readily conveyed to the 
washing room by the same method. 

Bottle Washing. — The simplest method of washing 
bottles is by means of a revolving brush as described under 
"The Village Milk Plant." But this is not economical 



Io6 DAIRY TECHNOLOGY 

when a great number of bottles must be washed and ster- 
ilized each day. The modern bottle-washer handles the 
glassware in cases, taking them in at one end, just as they 
come from the wagons, and delivering them at the other 
end perfectly clean and sterilized. 

In general there are two kinds of bottle washers: that 
in which brushes are used, and that in which jets of water 
are relied upon to do all the cleaning. 





Fig. 20. — A-F gravity conveyers in Gridley Dairy Co. plant, 
carrying bottles from wagons to basement. 

The automatic brush bottle washer soaks, washes with 
water under pressure and with brushes, and rinses and 
sterilizes the bottles. Sanitary cases may be used and the 
bottles kept in these cases during washing, filling, capping, 
and even on the wagon, so that separate handling of bottles 
is unnecessary. This not only saves a great deal of time, 
but also reduces the breakage to a minimum. In the 
operation of the machine, the cases of bottles are passed 
through the washer by means of a carrier, which operates 
automatically, stopping a sufficient length of time for 



THE CITY MILK PLANT 



1 07 








io8 



DAIRY TECHNOLOGY 



the various operations and discharging the bottles clean, 
practically sterile and hot. They dry quickly and assume 




Fig. 22. — Steam chamber, showing method of steaming bottles. 
(Circular 184, Dairy Division, U. S. Dept. of Agr.) 

a good clear luster. The washing process requires about 
five minutes. 

The high-pressure bottle washer operates similarly to 
the brush washer, except that in the former no brushes are 
used. The work of the brush is accomplished by jets of 
water under high pressure. Large quantities of water 



THE CITY MILK PLANT I09 

are pumped over and over again with great force against 
the bottles, both inside and outside. The water in the 
tanks is renewed automatically and continuously, a small 
stream of water coming in and a small stream of impure 
water running out. 

The Milk Bottle. — The only style of milk bottle used 
to any extent at the present time is that made of glass. 
The advantages of a glass bottle are as follows: 

1. It is easily cleaned and sterilized. 

2. The consumer can easily detect the presence of 

dirt of any kind in the bottle or the milk. 

3. It cannot itself impart any flavor to the milk, 

and forms a perfectly tight package to keep out all 
dirt, flavors, etc. 

4. It cannot corrode nor become unsanitary in any 

way, however old it may become. 

The disadvantages of a glass bottle are: 

1. It is fragile. 

2. It is costly. 

3. It is heavy. 

4. Unless sterilized before being filled it may become 

a carrier of disease. 

Because of these disadvantages, numerous attempts 
have been made to introduce a single-service container 
made of paraffined paper. This seems to be the only 
alternative to glass, all metals being out of the question. 
But the consumer cannot see the thickness of the layer 
of cream on the top, he cannot tell whether the milk in 
the paper container is clean or not, and the package is 
not so pleasing to the eye. These are the chief reasons 
for the failure of the single-service container to be gen- 
erally adopted. 



no DAIRY TECHNOLOGY 

The Bottle Cap. — Bottles of ordinary market milk 
are commonly capped with a pulp cap that fits into the 
countersink mouth of the bottle. This leaves the lip 
of the bottle exposed to the accumulation of dirt and 



Fig. 23. — This sliuws a {ypc nl' sanitary l)oUlc cap, and method of 
removing same. 

bacteria. When milk is poured from such a bottle it 
flows over and carries with it whatever contamination 
may be there. 

Producers of certified milk have adopted various de- 
vices to protect the lip of the bottle. Many of them use 



THE CITY MILK PLANT 



III 



the ordinary cap with a large hoodlike paper cap covering 
the entire top of the bottle. Others use a cap that fits 
tightly over the opening of the bottle, insuring a tight 
seal and protecting the lip at the same time. 

Another style of cap being introduced is that similar 
to the cap used on pop and 
beer bottles, a metal cap lined 
with a fiber disk. These caps 
can be used only on bottles 
made for this purpose. They 
are placed upon the bottle by 
a machine that forces the cor- 
rugated skirt of the metal 
crown under the locking ring 
of the bottle, thus forming a 
hermetically tight seal, remov- 
able only by means of a bottle 
opener. This crown effectu- 
ally protects the mouth of the 
bottle. Machines are on the 
market for automatically filling 
and capping bottles of this 
kind. With this system, milk 
can be pasteurized in the bottles and thus avoid possible 
contamination during cooling and filling of bottles. 

Business Principles. — The business of handling a 
large quantity of a perishable product demands close 
watchfulness on the part of the managers to avoid losses. 
The daily income and output of milk must be the same, 
as near as is possible to have it. Because of the per- 
ishable quality of the product, and because of the large 
quantity that must be handled in a short time each day, 
experienced help and efficient machinery are necessary. 




Fio. 24. — Another type of a 
sanitary bottle cap. 



112 



DAIRY TECHNOLOGY 




I'lG. 25. — The foot milk bottle 
crowning machine. 



The best of both, though 
high priced to start with, 
are cheaper in the long 
run. The retail milk 
business is one in which 
the sales are all for small 
amounts, hence the profit 
on each sale is very small. 
Success, therefore, de- 
pends upon a close atten- 
tion to minute details. 

One of the problems 
of greatest importance is 
how to keep a close check 
on thedeliverymen. The 
manager usually does 
not come in direct con- 
tact with the custom- 
ers; minor employees out 
through the city, away 
from the supervision of 
the employer, have to be 
trusted entirely with the 
dealings with customers, 
the handling of the en- 
tire finished product, the 
cash and the return of 
empty bottles. 

The following system 
of checking the drivers 
is being used successfully 
in several large plants: 
When the driver goes 



THE CITY MILK PLANT 1 13 

out in the morning he is charged with the number of bottles 
of milk, the number of tickets or sheets of tickets and the 
cash he has in his possession. When he returns from the 
trip, he is again checked up and must have a used ticket 
or cash to account for every bottle of milk disposed of. 
He should also have an empty bottle for each full one 
sold. This latter is rather difficult, unless there is some 




Fig. 26. — A motor truck sijccidlly LHjuipped for handling dair)' prodiu ts. 
In the service of the Shefiield farms, N. Y. 

incentive for the driver to return the empties. Probably 
the best way to prevent the loss of empty bottles is to 
scale the wage on a basis of the number of empty bottles 
returned. For instance, some companies pay their drivers 
one dollar per day and one cent for each empty bottle 
returned. Under this system the driver is pretty sure to 
induce his customers to have an empty bottle ready for 
him each day. 



CHAPTER XI. 

STANDARDIZATION OF MILK AND CREAM. 

To standardize milk is to bring the butter-fat content 
to a given per cent regardless of the quality of the milk 
produced by the cow. Standardizing milk usually is 
done by the producer, because he cannot afford to pro- 
duce, say, 5-per-cent milk, and sell it at the same price 
that 4-per-cent milk sells for. Neither can the consumer 
afford to pay for 5-per-cent milk when only 4-per-cent milk 
is delivered, so that some milk companies now guarantee 
their milk to contain a certain per cent of fat in return for 
a stated price to be paid by the consumer. 

Standardization of milk may be accomplished in the 
following cases: 

I. Where the per cent of fat is to be reduced by the 
addition of skim milk. 

(a) Quantity of standardized milk not specified. 

(b) Quantity of standardized milk specified. 

II. Where the per cent of fat is to be increased by the 
extraction of skim milk. 

(a) Quantity of standardized milk not specified. 

(b) Quantity of standardized milk specified. 

III. Where the per cent of fat is to be reduced by the 
addition of milk having a lower fat content. 

(a) Quantity of standardized milk not specified. 

(b) Quantity of standardized milk specified. 

114 



STANDARDIZATION OF MILK AND CREAM 



115 



IV. Where the per cent of fat is to be increased by the 
addition of milk having a higher fat content. 

(a) Quantity of standardized milk not specified. 

(b) Quantity of standardized milk specified. 

Formulas and Examples : 

I. (a) To obtain milk containing 3.2 per cent of fat, 
from milk containing 4 per cent of fat and skim milk. 

Draw a square. At the two left-hand corners write the 
numbers which represent the per cent of fat in the two 
liquids which are to be mixed. In the center of the square 



3.2 parts of ii milk 




8 parts of skimmilk 
Fig. 27. 4.0 parts of ■3.2fc milk 

write the number representing the percentage of fat re- 
quired. Then subtract the two numbers standing in 
line across the diagonals of the square and place the differ- 
ence at the remaining two corners in such a way as to 
have the difference stand in line with the minuend and 
subtrahend. These last two numbers will indicate the 
proportions to be taken of the fluids whose percentages 
stand in the same horizontal line. 

Since 3.2 : 0.8 : : 4 : i then we require 4 parts of 4 per 
cent milk and i part of skim milk to produce 5 parts of 
milk containing 3.2 per cent of fat. 



Il6 DAIRY TECHNOLOGY 

The following formula may be used when the percentage 
is a convenient number to work with: Divide the per 
cent of fat in the milk that is desired by the per cent of 
fat in the milk on hand. The result will be the per cent 
of the milk on hand to be taken. The remaining per cent 
of milk will be the skim milk to be used. 

The correctness of the graphical illustration, Fig. 27, 
may be proven as follows: 

Let p be the per cent of fat in the cream of the richer of 
the two milks. 

Let q be the per cent of fat in the milk of the poorer of 
the two milks. 
Let r be the per cent of fat required, 

X be the quantity of richer milk required, 
y be the quantity of thinner milk required. 

Then px is the fat in the richer milk for new mixture, 
qy is the fat in the poorer milk of new mixture, 
{x + 3^) is quantity of new mixture, 
r {x-\- y) is the fat in new mixture, 
px + qy is the fat in new mixture. 
Therefore, px + qy = r {x -\- y). 
Solving, px-\-qy = rx + ry. 

px — rx = ry — qy. 
x{p — r) = y{r — q). 

Then dividing both sides of the equation hy y {p — r) 
we have 

X _ r — q 
y p —r 

Substituting with figures from the above example we have 

3-2 3-2 



STANDARDIZATION OF MILK AND CREAM I17 

In the above example we would have 3.2 -^ 4 = 0.80. 
Hence 80 per cent of 4-per-cent milk and (100 — 80 = 20) 
20 per cent of skim milk will produce milk containing 3.2 
per cent of fat. 

I. (b) To obtain 100 pounds of milk containing 3.2 per 
cent of fat from milk containing 4 per cent of fat, and skim 
milk. 

Determine the number of pounds of fat required. Divide 
this number by the per cent of fat in the known milk. This 
will give the pounds of known milk required. 

100 X 3.2 per cent = 3.2 which is the pounds of fat in 
100 pounds of 3.2 per cent milk. 

3.2 4-4 = 0.80 or 80 per cent, which is the proportion 
of 4-per-cent milk required to make 3.2-per-cent milk, 

80 per cent of 100 pounds = 80 pounds, the required 
pounds of 4-per-cent milk. 

100 — 80 = 20, the required pounds of skim milk. 

II. (a) To obtain milk containing 4 per cent of fat from 
milk containing 3.2 per cent of fat by the extraction of skim 
milk. 

x(s — r) 
s 



pounds of skim milk to be removed. 



When r = the per cent of fat in the known milk, 

5 = the per cent of fat in the standardized milk, 
X = the pounds of known milk. 

By substituting in the formula 

X (4. — ^.2 ) 

~ — — 0.2 o; = pounds of skim milk to be removed. 

4 

By removing from a given quantity of 3.2 per cent 
milk, skim milk equal to 0.2 of the weight of that milk, 
4-per-cent milk will be obtained. 



ii8 



DAIRY TECHNOLOGY 



II. (b) To obtain loo pounds of milk containing 4 
per cent of fat from milk containing 7^.2 per cent of fat by 
the extraction of skim milk. 

Find pounds of fat required. Then divide the desired 
pounds of fat by the per cent of fat in the known milk and 
multiply the quotient by 100. The difference between 
this product and the pounds of standardized milk is the 
pounds of skim milk to be extracted. 

(4 -^ 3.2) X 100 = 125, which is the pounds of 3.2-per- 
cent milk required to make 100 pounds of 4-per-cent milk. 

125 — 100 = 25 which is the pounds of skim milk to 
be extracted. 

III. (a) To obtain milk containing 3.5 per cent of fat 



3 parts of ^'^ milk 




^ parts of 3.25$ milk 
,8 parts of 3.5^ milk 

from milk containing 4 per cent of fat, by the addition of 
milk containing 3.2 per cent of fat. 

Same method as is used in solving I. (a). 

III. (b) To obtain 160 pounds of milk containing 3.5 
per cent of fat from milk containing 4 per cent of fat, by the 
addition of milk containing 3.2 per cent of fat. 

Same formula as is used in solving I. (a). 

0.8 : 160 : : 0.3 : 60. Hence 60 pounds of 4-per-cent 
milk are required. 



STANDARDIZATION OF MILK AND CREAM 119 

0.8 : 160 : : 0.5 : 100. Hence 100 pounds of 3.2-per- 
cent milk are required. 

IV. (a) To obtain milk containing 3.5 per cent fat 
from milk containing 3.2 per cent of fat by the addition of 
milk containing 4-per-cent milk. 

Same formula as used in solving I. (a). 

IV. (b) To obtain 160 pounds of milk containing 3.5 
per cent of fat from milk containing 3.2 per cent of fat by 
the addition of milk containing 4 per cent of fat. 

Same problem as in III. (b). 

Standardization of Cream. — The standardization of 
cream is of still greater importance than the standardiza- 
tion of milk, because the variation of the percentage of 
fat in cream is relatively greater than that of the milk. 
The fat content of cream under normal conditions varies 
between 10 per cent and 50 per cent, while that of milk 
seldom varies over 2 per cent or 3 per cent. 

When a certain volume of cream is being sold, a com- 
paratively larger amount of butter fat is disposed of than 
when the same volume of milk is sold. As it is the butter 
fat which is the most valuable part of cream and milk, 
it is a good plan to regulate the price of cream according 
to (1) the percentage of fat in the cream, (2) the current 
price of the butter or butter fat. 

Even when the same separator is being used daily, the 
percentage of fat in the cream is likely to vary as much as 
5 per cent. This variation, if cream is not standardized, 
may cause a considerable loss to either consumer or pro- 
ducer. For instance, suppose 25 gallons of cream should 
contain 20 per cent of fat, and it was unknowingly increased 
to 25 per cent, there would than be 5 per cent more than 
the standard required. If this cream were sold at 80 cents 
a gallon, the price per pound of fat in the first case would 



I20 DAIRY TECHNOLOGY 

be 50 cents. If the cream tests 25 per cent instead of 20 
per cent, 0.4 of a pound of fat too much is given in each 
gallon of cream. In 25 gallons of cream 10 pounds too 
much would be given. This, at 50 cents per pound, would 
make a loss of $5.00 to the producer from the sale of 
25 gallons alone. Such a loss would affect the profit 
directly. 

The principal difference between milk and cream is 
that cream contains a larger per cent of fat than does 
milk. For this reason, the same methods which apply to 
the standardization of milk will also apply to the standard- 
ization of cream. 

When the cost of butter fat is to be taken into consider- 
ation, then a separate process must be applied. If it is 
desired to find the price of butter fat when so much is 
obtained per gallon, then first multiply the pounds of 
cream per gallon by the per cent of butter fat in the cream. 
The product will equal the pounds of fat per gallon of 
cream. Then divide the price per gallon of cream by the 
number of pounds of butter fat. The quotient will be 
the price per pound of butter fat. 

Example. What is the price per pound of butter fat 
when cream containing 20 per cent of fat sells for 50 cents 
per gallon? 

A gallon of cream weighs about 8 pounds. 

8 pounds X 0.20 = 1.60 pounds of fat in a gallon of 
cream. 

.50 divided by 1.6 equals $0.31, the price of a pound of 
butter fat. 

If it is desired to calculate the price of a gallon of cream 
when butter fat is worth a certain price, then multiply the 
pounds of cream per gallon by the per cent of fat in the 
cream. The product will represent the number of pounds 



STANDARDIZATION OF MILK AND CREAM 121 

of butter fat in one gallon of cream. Multiply this prod- 
uct by the price per pound of butter fat desired. The 
product will represent the price per gallon of cream. 

Example. At 30 cents per pound of fat what would 
be the price of a gallon of cream containing 25 per cent 
of butter fat? 

8 X 0.25 = 2 pounds of butter fat. 

2 X 30 cents = 60 cents, the price per gallon of cream 
testing 25 per cent of fat. 

In case it is desired to make use of butter prices, it is 
essential to increase the fat by the average overrun. 

If it is desired to find the equivalent price per gallon 
of cream containing different per cents of butter fat, the 
following method is the quickest. 

Example. If cream containing 20 per cent of fat is 
worth 60 cents per gallon, what is cream worth containing 
25 per cent of fat? 

0.20 : 0.25 : : 0.60 : x. 
60 X 0.25 = 15. 

15 divided by 20 equals 0.75, the equivalent price of 25- 
per-cent cream. 

In some instances, cream is sold for so much per quart 
for each per cent of fat it contains. The usual price when 
sold in this way is one cent per quart for each per cent of 
fat it contains. For instance, if the cream contains 25 
per cent of fat, then the price of it would be 25 cents per 
quart. If it contained 35 per cent of fat, it would be 
worth 35 cents per quart, etc. In case the quality of 
cream varies, this is a fairly good basis upon which to fix 
the price of cream. 

In all instances, when milk or cream is being standard- 
ized, care should be taken not to mix old cream with fresh 
milk, or vice versa. Old cream and fresh milk, in the first 



122 DAIRY TECHNOLOGY 

place, do not mix as well as when both are fresh. Lumps 
of cream are likely to remain, even though it may seem as 
if the two had been mixed well. Thus an unattractive 
appearance is caused. Secondly, the older cream or milk, as 
a rule, contains a large number of bacteria, and in some 
instances undesirable ones. These when mixed with the 
good milk will cause the keeping property of the whole to 
be lessened, and in some instances cause the whole mixture 
to assume abnormal qualities. 



CHAPTER XII. 

SANITARY EXAMINATION OF MILK. 

Several cities have adopted bacterial standards for milk. 
Rochester, N. Y., requires that the bacterial content of 
their city milk be kept below 100,000 per cubic centimeter. 
Boston permits 500,000 per cubic centimeter, and other 
cities have different requirements for different grades of 
milk. 

The number of bacteria in milk cannot be determined 
until 24 to 48 hours after the sample was taken, by which 
time the milk has been consumed. A milk dealer demands 
a quicker test for the quality of the milk. Since the age 
of milk is indicated somewhat by the degree of acidity, 
the acid test is used to some extent to determine the 
quality of the milk. 

Acidity Test. — The simplest method of determining 
roughly the acidity of milk is by the use of Farrington's 
Alkaline Tablets, using a solution made of one tablet to one 
ounce of hot water. Using the same unit for the measure- 
ment of both, the milk and the alkaline solution, one volume 
of alkaline solution added to one volume of milk will neu- 
tralize acid equivalent to one-tenth of one per cent. If the 
addition of two volumes of alkaline solution to one of cream 
does not neutralize all the acid (turn the milk pink), then 
that milk contains more than two-tenths of one per cent 

acid, and is not a first-grade product. 

123 



124 



DAIRY TECHNOLOGY 



Sediment Test. — The cleanliness of milk is indicated 
somewhat by the amount of dirt or sediment it contains. 
There is no way of extracting all the dirt that may have 
fallen into the milk during or subsequent to milking, be- 
cause nearly one-half of ordinary barn dirt is soluble; 
hence the presence of a small quantity of visible dirt is 
usually an indication that a greater quantity is present 




Fig. 29. — The Wisconsin milk sediment tester. 

in the milk. The cleanliness of milk may be roughly 
ascertained by centrifuging a sample, or by filtering a 
certain volume through absorbent cotton and noting the 
amount of discoloration and filth deposit on the filter. 
Tests for this latter purpose are manufactured and offered 
for sale. 

Babcock and Farrington describe a milk-sediment test 
devised by them in which one pint of milk is placed in a 



SANITARY EXAMINATION OF MILK 125 

steam-heated jacketed container, and filtered through a 
disk of absorbent cotton, said cotton to be free from sizing 
or starch, which prevents satisfactory filtering of the milk. 
Milk may* be graded according to the degree of discolora- 
tion of the cotton. 

Leucocytes in Milk. — In the milk of normal, healthy 
cows may be found a number of leucocytes or white-blood 
corpuscles. The mixed milk from a healthy herd seldom 
contains more than 500,000 cells per cubic centimeter, 
although this number is often exceeded in the milk of indi- 
vidual cows. An inflamed or diseased condition of the 
udder causes a great increase in the leucocyte content of 
the milk, hence, at the present time, milk containing over 
500,000 of these bodies per cubic centimeter is looked upon 
as coming from a bruised or inflamed udder and is con- 
sidered unfit for food. However, this number cannot be 
adopted as a set standard, but it is well to class all milk as 
suspicious when it does exceed this limit. A physical exami- 
nation of the cows producing the milk should be made and 
action taken according to the findings at this examination. 

Fibrin has been found to accompany leucocytes, es- 
pecially in acute cases. Professor Doane found that when 
a cow's udder is badly inflamed these fine threads, or fibrin, 
are found in the milk. The leucocytes in such milk also 
tend to hang together in clusters. In some experiments 
with milk from an inflamed udder, Doane found as many as 
20,000,000 leucocytes per cubic centimeter of milk. Fibrin 
was also found in this milk. As the cow's udder became 
well, the number of leucocytes dropped to 500,000 per cubic 
centimeter. At this period, the fibrin disappeared. A 
number of counts were made from milk of different cows, 
and it was found that fibrin accompanied a large number 
of leucocytes. 



126 DAIRY TECHNOLOGY 

Reduction-Fermentation Test. — This test was origi- 
nated by Barthel of the Swedish Experiment Station and 
is used as follows: To 20 cubic centimeters of milk add 
C.5 cubic centimeter methylene blue and 2.5 per cent satu- 
rated alcoholic solution in water. Keeping the samples at 
about one hundred degrees F., the rapidity of the reduc- 
tion of the color, the change from blue to white, varies 
directly as the number of bacteria in the milk. This re- 
duction test is combined with the fermentation test by 
keeping the samples until curdling takes place and noting 
the time required to curdle and the presence of gas or bad 
flavors in the curd. 

According to Barthel, if the milk contains several hundred 
thousand bacteria per cubic centimeter, reduction will take 
place within fifteen minutes. If the blue color disappears 
within an hour, the milk is not first class. One to three 
hours are required for the reduction in high-grade market 
milk, but even a greater length of time is required for very 
fresh, clean milk. 

Of course, this test is merely an indication of the numoer 
of bacteria present, but it may be found very useful to the 
dealer trying to buy a high-grade milk, or to the butter 
or cheese maker, who wishes to guard against the evils of 
over-ripe milk. • , 



CHAPTER XIII. 

WHIPPING OF CREAM. 

Conditions Affecting Viscosity of Cream. — When creg,m 
is pasteurized, heated, or even warmed, the clusters of 
fat globules are broken up. This lessens the viscosity 
of the cream to such an extent that it does not whip so 
readily. It has the consistency of raw cream of a lower 
per cent of fat. This frequently misleads the consumer to 
think the cream is not up to standard in fat. The vis- 
cosity may be restored by holding the cream at a low tem- 
perature for a day, or at least 12 hours, but this is not 
practicable in city milk supply. Another way to restore 
the viscosity to cream as investigated by the Wisconsin 
Experiment Station is to add sucrate of lime, known 
commercially as " Viscogen." Cream containing visco- 
gen must be so labeled because our pure food laws forbid 
the addition of any substance to milk or cream. The name 
" visco-cream " has been used to designate this product. 
Preparing Viscogen. — Viscogen may be made as follows : 
Dissolve 2I parts granulated sugar in 5 parts water; 
slake I part good rock-lime in 3 parts water. Pour the 
slaked lime through a wire strainer to remove coarse, 
undissolved particles and add to the sugar solution. 
Agitate the mixture occasionally for two to three hours, 
then allow it to settle for about twelve hours or until the 
liquid becomes clear, when it can be siphoned off and is 

ready for use. 

127 



128 DAIRY TECHNOLOGY 

Viscogen should be kept in air-tight containers, be- 
cause, when exposed, it absorbs carbon dioxide from the 
air and is weakened. Exposure to the air for a long time 
also darkens the solution, but this does not impair its 
usefulness. 

The function of sugar in viscogen is to hold lime in 
solution. A sugar solution of equal parts of sugar and 
water will hold about one hundred times as much lime 
as 'is found in plain lime water. 

Use of Viscogen in Cream. — One part of viscogen to 
from one hundred to one hundred and fifty parts of cream 
will produce the desired results. An excess of this 
substance imparts a soapy flavor to the cream, hence 
the following method of adding viscogen is recom- 
mended. 

Titrate a small quantity of cream with the viscogen 
that is to be used, and calculate the quantity of viscogen 
required to neutralize (to phenolphthalein) all of the acid 
in the cream; then add from one-half to two-thirds this 
quantity. 

For example: We have 800 pounds of 25 per cent 
cream, pasteurized. We wish to restore its viscosity by 
the addition of viscogen. Put some of the viscogen into 
a burette graduated in cubic centimeters, such as is used 
for Manns' acid test. Place a sample of cream, 35 cubic 
centimeters, or any convenient amount, in a white cup, 
add two or three drops of phenolphthalein, and then run 
in viscogen from the burette until a permanent faint pink 
color is secured. If the quantity of viscogen used to 
neutralize the acid in 35 cubic centimeters of cream was 
0.6 cubic centimeter, then to neutralize the acid in 800 
pounds of cream would require: 

35 : 0.6 : : 800 : x or 13.7 pounds. 



WfflPPING OF CREAM 1 29 

But we wish to neutralize only one-half of the acid in the 
cream, so we require but one-half of 13.7 or 6.8 pounds of 
viscogen. 

Pasteurized cream should be cooled to 60° F. or less 
before the viscogen is added; this is to avoid the produc- 
tion of an undesirable alkaline flavor. 

The retailer of cream and the consumer should both be 
well posted on the influence of various conditions on the 
whipping quality of cream. 

The greater the per cent of fat in cream, the better 
the cream will whip ; but an excess of fat is not necessary 
or even desirable, and, if proper conditions are secured, 
cream containing 25 to 30 per cent of fat can be whipped 
until it stands alone. 

Other conditions being observed the colder the cream 
(freezing point being the limit) the better it will whip. 
This is a very important point for the cook to observe, 
because cream that will produce an excellent whip at 50° F. 
can be only fair when whipped at 60° F. Failure to secure 
a good whip is too often due to the warming of the 
cream during the whipping; cream at 50° F. brought into 
a warm kitchen, placed in a warm dish, and having warm 
air beaten into it, will possibly acquire a temperature 
of 65° to 70°. Under such conditions it is doubtful if the 
whipping will produce good results; but if the same cream 
be whipped in a cold vessel, in a cool room, much better 
results will be secured. 

Cream 24 hours old will whip better than fresh cream. 
This is due to the blending together of the various milk 
components, and to the gathering of the fat globules into 
clusters which increase the viscosity of the cream. The 
same result may be secured to a certain extent by the 
addition of viscogen, 



I30 



DAIRY TECHNOLOGY 



C. W. Melick ^ notes the following points affecting the 
whipping of cream : 

" I. There was no difference in the whipping qualities 
of gravity and separator cream. When any difference is 
experienced it is due to other factors and not to the method 
of getting the cream from milk. 

2. Cream for whipping purposes should contain at 
least 20 per cent butterfat. The results were obtained 
with cream containing from 25 per cent to 40 per cent 
butterfat. 

3. For best results cream should be held at as low a 
temperature as possible (35° to 45° F.) for at least two 
hours before whipping, and should be whipped in a cool 
room. 

4. For good results cream should be from 12 to 24 
hours old. This gives an opportunity for the develop- 
ment of a small amount of acid in the cream. The acid 
effected a gelatinous consistency in the casein and albumin 
and thus facilitated the incorporation of air in whipping. 
When it is desired to whip fresh cream, -^-q per cent commer- 
cial lactic acid may be added to take the place of the acid 
which would develop by setting the cream from 12 to 24 
hours. 

5. Pasteurized cream may be whipped as easily as un- 
pasteurized cream if it is thoroughly cooled and held at 
35° to 45° F. for at least two hours before whipping. 

6. For good results cream should whip in from 30 to 
60 seconds. When a longer time is required there is danger 
of some of the butterfat separating or churning. 

7. The addition of one-tenth per cent of commercial 
lactic acid to cream facilitated its whipping and made 
it possible to whip cream which was fresher, which con- 
tained less butterfat and which was warmer than is ad- 
visable for the best results. 

8. The use of viscogen facilitated the whipping of cream 
to a greater extent than any other ingredient with the 
exception of lactic acid. It proved less effective than the 

^ Maryland Bid. 136. 



WHIPPING OF CREAM 131 

latter and also less effective than a low temperature. 
The addition of viscogen caused cream to remain sweet 
from 12 to 24 hours longer than it otherwise would. 

9. The use of powdered sugar, powdered milk, salt, 
caramel, gelatine, junket, and cornstarch, each facili- 
tated the whipping of cream to a small degree, and each 
to practically the same extent. None of them proved 
as effective as a low temperature and the development 
or addition of lactic acid. The addition of an excess of 
gelatine above 10 per cent, or of cornstarch above 20 per 
cent caused a lumpy cream when whipped. 

10. The use of egg albumen with cream when whipped 
separately and mixed, produced a lighter foam, but had 
no effect upon the time required to whip. When mixed 
before the egg albumen was whipped, at temperatures 
above 40° F., the whipping was retarded. 

11. The use of vanilla extract used in ordinary quan- 
tities had no effect upon the whipping qualities of cream. 

12. The charging of cream with carbonic acid gas with- 
out pressure had no effect on its whipping qualities but 
caused it to remain sweet from 12 to 24 hours longer. 

13. The use of cream from cows near the end of their 
lactation period whipped with slightly more difficulty 
than did cream from fresh cows. 

14. Whipped cream will not keep sweet as long as un- 
whipped cream. 

15. When any additions are made to cream to facili- 
tate whipping it should be so labeled as to not deceive the 
purchaser." 



PART III. 
ICE-CREAM MAKING. 

CHAPTER XIV. 

fflSTORY AND EXTENT OF ICE-CREAM MAKING. 

Alexander the Great is said to have been very fond of 
iced beverages, and it is said that one of our modern vari- 
eties, the "Macedoine," was named after the ancient Mace- 
donian. Wines and fruit juices were cooled with ice and 
snow at the courts of France and Italy in very early times. 
When and where the first water ices were made no one can 
say, but it seems probable that they were brought to France 
from Italy by Catherine de Medici in the sixteenth cen- 
tury. Marco Polo is reported to have brought recipes for 
water ice and milk ice from Japan in the thirteenth century. 

Cream ice was served at a banquet given by Charles I of 
England. This ice was made by a French cook named De 
Mireo, and it is related that the king was so well pleased 
with the new dish that he pensioned the cook with 20 pounds 
a year on condition that the latter should not make the 
ice for any one but the king, and should tell no one else how 
to make it. 

English cook books, published about the middle of the 
eighteenth century, gave recipes for making cream ices. 

It can readily be seen how the making of ice cream has 
developed step by step from the cooling of wines and fruit 

132 



HISTORY AND EXTENT OF ICE-CREAM MAKING 133 

Juices to the freezing of similar liquids, and then to the 
freezing of milk and cream. 

Ice cream is said to have been introduced to the city of 
Washington, by Mrs. Alexander Hamilton, at a dinner 
that was attended by George Washington. 

The first ice cream advertisement on record is one that 
appeared in the " Post Boy," New York City, June 8, 







Fig. 30. — View of large ice cream plant. (Ice Cream Trade Journal.) 



1786. At this time, ice cream sold readily at one dollar 
per quart. 

Jacob Fussell, so far as known, was the first man to make 
a wholesale business of ice-cream making. He was a milk 
dealer in Baltimore, Md., and adopted ice-cream making 
to utilize his surplus cream. A few years later, an ice 
company, becoming interested in the manufacture of ice 
cream, paid Fussell S500 for teaching one of their men the 
art of making this product. 



134 DAIRY TECHNOLOGY 

American enterprise took up the new industry, and it 
developed steadily. However, it was not until after 1890 
that the rapid growth began. Since that date the business 
has been growing with increasing rapidity, aided, to some 
extent, by the perfection of artificial refrigeration. This 
provided a way for these frozen dainties to be used in the 
south, and made possible the great wholesale factories 
found in some of our large cities. 

The value of the ice cream consumed in this country 
has reached the enormus figure of $150,000,000^ per annum 
and has outgrown the small and secret chamber in which 
the manufacturer of a few years ago performed his work. 

The making of ice cream has been regarded, at least in 
part, as a secret process. During the few years that ice 
cream has been made on a commercial scale, and even to- 
day, in many places, the mixing and freezing of ice cream 
are carried on behind locked doors, too often in cellars. 
But it is the opinion of many of the large manufacturers 
that the time has come when secrecy is not necessary, nor 
even desirable. The making of ice cream in secret does 
not create a monoply for the manufacture, nor does it 
increase the popularity of or demand for the product. On 
the other hand, the making of ice cream in a modern, 
properly constructed, sanitary factory, open to the public, 
is a great advertisement for the manufacturer and is con- 
ducive to an increased demand for the product. Manu- 
facturers of ice-cream supplies are scattering broadcast 
exact directions for making the mix, freezing the cream, etc. 
Several dairy schools are teaching commercial ice-cream 
making. Some large dealers are promulgating the opinion 
that ice-cream making is a scientific process, and that the 

^ John Gordon — Address at Second Annual Convention of Iowa Ice 
Cream Makers' Association. 



fflSTORY AND EXTENT OF ICE-CREAM MAKING 135 

more the subject is made public, is discussed and studied, 
the more perfect will the process become and the better 
will the product be. The better the product, the greater 
the consumption of the same. 

Classification of Ice Creams and Ices. — Ice creams may 
be divided into many classes. Their differences are some- 
what indefinite. However, there are three great divisions 
commonly known and recognized throughout this country. 
These are: 

I. Philadelphia Ice Cream. 

Made up of cream, sugar, flavoring, and usually a 
binder. Under this heading the following would be 
included: Plain ice cream, nut ice cream, fruit ice 
cream, chocolate ice cream, coffee ice cream, macaroon 
ice cream, etc. 

II. Neapolitan Ice Cream. 

This differs from the first class chiefly in that it 
always contains eggs. This kind of ice cream admits 
of wide varieties and may resemble in composition and 
consistency a frozen pudding more than an ice cream. 

III. Fancy Ice Cream. 

This kind of ice cream differs chiefly from the 
Philadelphia Ice Cream in the manner of molding or 
printing, and in the coloring. 

1. Brick Ice Cream. 

This is usually made up in pint, quart and two- 
quart sizes. It is made in layers. Any of the ice 
creams may be used for this purpose. 

2. Indi\ddual Molds. 

These molds are shaped to imitate some object 
(fruit or animal). The ice cream object may be 
colored in imitation of the object it represents. 



136 DAIRY TECHNOLOGY 

Associated with ice cream are numerous other ices, 
none of which, however, are dairy products. These are 
usually considered under the following heads. 

IV. Ices. 

1. Water ice is fruit juice diluted with water to the 
proper degree, sweetened and frozen the same as is ice 
cream. Its texture is quite different from that of ice 
cream. The latter is smooth and velvety, while the former 
is grainy, being more like firm, wet snow in texture. 

2. Sherbet sometimes closely resembles ice cream 
in appearance, body, and texture. However, no cream or 
milk is used in this ice. Its creamy appearance is due 
to the presence of beaten white of egg, gelatin, or other 
binders. Sherbet is composed of fruit juice, water, sugar, 
white of egg, and, sometimes, a binder. If beaten vio- 
lently until frozen hard the result will be a fine, smooth, 
creamy ice. If frozen with but slight agitation or only 
half frozen, the result will be a more granular texture. 

3. Sorbet is a name sometimes applied to sherbets 
of fine, smooth texture. 

4. Granites are water ices only half frozen without 
much stirring, having a coarse icy texture. 

5. Frozen Punches are made by adding one or more 
liquors or cordials like champagne, maraschino, Jamaica 
rum, etc., usually after the freezing is nearly or entirely 
completed. 

The following classification has been adopted by Prof. 
Mortensen at the Iowa Experiment Station:^ 

I. Plain Ice Creams. 
II. Nut Ice Creams. 
III. Fruit Ice Creams. 

1 Ames, Iowa Bui. 123. 



fflSTORY AND EXTENT OF ICE-CREAM MAKING 137 

IV. Bisque Ice Creams. 
V. Parfaits. 
VI. Mousses. 
VII. Puddings. 
VIII. Aufaits. 
rX. Lactos. 
X. Ices. 

1 . Sherbets. 

2. Milk Sherbets. 

3. Frappes. 

4. Punches. 

5. Souffles. 

I. Plain ice cream is a frozen product made from 
cream and sugar with or without a natural 
flavoring. 
II. Nut ice cream is a frozen product made from 
cream, sugar and sound, non-rancid nuts. 

III. Fruit ice cream is a frozen product made from 

cream, sugar and sound, clean, mature fruits. 

IV. Bisque ice cream is a frozen product made from 

cream, sugar and bread products, marshmallows 

or other confections, with or without natural 

flavoring. 
V. Parfait is a frozen product made from cream, 

sugar and egg yolks, with or without nuts or 

fruits and other natural flavoring. 
VI. Mousse is a frozen whipped cream to which 

sugar and natural flavoring have been added. 
VII. Pudding is a product made from cream or milk, 

with sugar, eggs, nuts and fruits, highly flavored. 
VIII. Aufait is brick cream consisting of layers of one 

or more kinds of cream with solid layers of 

frozen fruit. 



138 DAIRY TECHNOLOGY 

IX. Lacto is a product manufactured from skimmed 
or whole sour milk, eggs and sugar, with or 
without natural flavoring. 
X. Ices are frozen products made from water or 
sweet skimmed or whole milk and sugar, with 
or without eggs, fruit juices, or other natural 
flavoring. 

Ices may, for convenience, be divided into sherbets, 
milk sherbets, frappes, punches and soufiies. 

1. Sherbet is an ice made from water, sugar, egg 
albumen and natural flavoring, and frozen to the con- 
sistency of ice cream. 

2. Milk sherbet is an ice made from sweet skimmed 
or whole milk with egg albumen, sugar and natural flavor- 
ing, frozen to the consistency of ice cream. 

3. Frappe is an ice consisting of water, sugar and natural 
flavoring, and frozen to a soft semi-frozen consistency. 
Same formulas as are given for sherbets will answer for 
frappe by omitting the egg albumen. 

4. Punch is a sherbet flavored with liquors, or highly 
flavored with fruit juices and spice. 

5. Soufiie is an ice made from water, eggs, sugar and 
flavoring material. It differs from sherbets mainly in 
that it contains the whole egg. 



CHAPTER XV. 

CREAM FOR ICE-CREAM IMAKING. 

In the manufacture of ice cream, the best cream to use 
is perfectly sweet, fresh cream. Cream of the highest 
quality must be produced by healthy cows, properly fed 
and cared for under perfectly sanitary conditions. It 
must be handled only in clean containers, kept cold and 
deUvered daily to the factory. 

Too much emphasis cannot be placed upon the subject 
of quality of cream. Ice cream is valued mainly because 
of its pleasing flavor and refreshing effect. Hence the pres- 
ence of any undesirable flavor is much more objectionable 
in this product than in other staple foods. 

Acidity. — An acidity of the cream above 0.25 per cent 
is too great for ice-cream making, and should not be used 
at all, or it may be reduced by the addition of very sweet 
cream. In dire need, cream not too sour and old may be 
partly reduced in acidity by adding some harmless neu- 
trahzer. Ice-cream made from such raw material should 
be labeled accordingly. The acidity of the cream may be 
reduced two-tenths per cent without greatly impairing the 
flavor, but too great an addition of alkali must be avoided 
because of the abnormal flavor it imparts to the cream. 
An excess of alkalinity is more objectionable than slightly 
acid cream. When reducing the acidity of cream, it is best 
to use an acid test, calculate the amount of neutralizer 
required, and add just enough to bring the per cent acid 
to the point desired, not lower tban to 0.2 per cent acid. 

139 



140 DAIRY TECHNOLOGY 

One part of viscogen to i8o parts of cream will reduce 
the acidity of the cream about o. i per cent. 

Homogenized Cream. — The process of homogeniza- 
tion consists of passing heated cream (140° F. to 180° F.), 
through a machine known as a homogenizer. The func- 
tion of the machine is to break the fat globules into such 
tiny particles that they cannot be separated from the serum 
by gravity nor even by centrifugal force, except to a small 
extent. This insures an absolutely uniform emulsion of 
all the solids in the cream. Another effect of this process 
is a great increase in the viscosity of the cream. Homo- 
genized cream containing fourteen per cent fat has about the 
same consistency as fresh, raw cream containing 18 per 
cent fat. 

Homogenized cream may be produced in three different 
ways: 

(i) By using natural cream. 

(2) By mixing skim or whole milk and butter in such 
proportions that the resulting product will be cream of the 
desired per cent of fat. 

(3) By mixing butter, milk powder and water in such 
proportions that the resulting mixture will have approxi- 
mately the same composition as a natural cream. 

Some large ice-cream manufacturers store quantities 
of unsalted " June Extras" butter to be used in the busy 
season, when it is difficult to secure an ample supply of 
fresh cream. 

Pasteurization. — The thorough pasteurization of sweet 
cream destroys about ninety-nine per cent of the bacteria 
present, and hence causes the cream to keep sweet a much 
longer time. But the heating of the cream breaks down 
the clusters of fat globules, renders the cream less viscous, 
and apparently poorer or lower in fat content. The ice- 



CREAM FOR ICE-CREAM MAKING 141 

cream maker desires a thick, viscous cream, so he generally 
objects to pasteurization. It has been found that when 
cream is allowed to stand at a low temperature (about 
40° F.) for 24 hours after pasteurization, it yields as large 
a volume of good bodied ice cream as does raw cream kept 
under similar temperature conditions for the same length 
of time. Hence pasteurized cream may be used successfully 
in ice-cream making, if it is allowed to reestablish its 
viscosity. 

Aging and Cooling. — It is a recognized fact among ice- 
cream makers that, in order to obtain the proper yield and 
texture, it is necessary to hold the cream over night, and 
even for 24 hours, at a low temperature before freezing. 
During this time its viscosity is greatly increased. It is 
especially important to age pasteurized cream in order to 
secure good results. Cream that is to be held for 24 hours 
must be kept cold, first, in order to prevent souring, and 
second to increase the viscosity. Cream with such charac- 
teristics produces ice cream which has better body and tex- 
ture, just as butter has a better grain and body if the 
cream is held at a low temperature for two or more hours 
before churning. 

When aging cream, the aim should be to keep it as cold as 
possible without freezing. This can be done most readily 
by placing the cans of cream in a well-covered and well- 
insulated tank containing a mixture of water, ice and some 
salt. 

Fat Content. — From the quality standpoint, the ideal per 
cent of fat in cream for ice-cream making is about twenty, 
(before the sugar, etc., is added, or fourteen to seventeen 
per cent in the mix). A much richer cream than this is 
likely to be too rich and buttery. Some people like the 
flavor of extra rich cream, but most prefer ice cream of 



142 DAIRY TECHNOLOGY 

medium richness. A large dish of exceedingly rich ice 
cream is likely to cause indigestion, and a smaller quantity 
of it is consumed. Insufhcient fat in the cream, unless an 
excess of filler is used, produces a coarse granular icy tex- 
ture, which is not desirable, and a lower overrun is also ob- 
tained from such cream. From a health standpoint ice 
cream containing about fourteen per cent of fat is prefer- 
able. From such cream, good palatable ice cream having a 
desirable body can be obtained. A proper overrun can also 
be obtained from cream of this richness. 

From the manufacturer's standpoint, a low fat content 
may seem desirable. At places where ice cream is sold 
without the maker's name being known, and without legal 
restrictions, we find ice cream containing as low as four to 
six per cent of fat. This is commonly known as circus or 
picnic ice cream. However, the manufacturer trying to 
establish a favorable market for his goods must produce 
the best possible quality. 

National and some state laws specify that ice cream shall 
contain a certain per cent of butter fat, usually fourteen 
per cent. 



CHAPTER XVI. 

PREPARING THE MIX. FILLERS AND BINDERS. 

Flavor. — The flavor of ice cream is dependent chiefly 
upon three things: the cream itself, the flavoring extract 
or fruit added, and the sugar. 

The necessity for good-flavored cream for ice-cream mak- 
ing has already been discussed. 

The kinds of flavoring extracts that may be used are 
too numerous to mention. The quantity will depend upon 
the brand used. The concentration of extracts varies 
widely, and it is notable that the same firm occasionally 
makes single, double and triple strength extracts. Hence 
it is a good practice to find one suitable extract and use 
that brand exclusively; but most important of all is to 
have the very highest quality of extract that can be ob- 
tained. The different kinds of flavoring substances may 
be grouped as follows: 

1. Crushed fruits with their juices. 

2. Extract flavorings. 

3. Sweetening. 

I. The crushed fruits of the various kinds are at all 
times to be preferred. These, however, are not always 
obtainable, and when out of season they are expensive. 
For these reasons, the crushed fruits cannot always be used 
for flavoring ice cream. The extract flavorings are used 
largely in connection with the manufacturing of ice cream 
on a commercial scale. When ice cream is manufactured 

143 



144 



DAIRY TECHNOLOGY 



for home use, in a small way, crushed fruits are to be pre- 
ferred. During the season that ice cream is manufactured 
on a small scale, fresh fruits are usually obtainable. About 
two ounces of crushed fruit to each pound of cream will be 
found to produce the proper flavor. The amount will vary 
a little'according to the likes and dishkes of the consumer 
and according to the degree of concentration of the fruit. 




Fig. 31. — The Wizard ice cream mixer. 



The crushed fruit may be added to the cream just pre- 
vious to putting it into the freezing can, but at this time 
there is some danger of coagulating the cream. The acid 
in the fruit affects the cream to some extent. It is pref- 
erable to add the crushed fruit and juice to the ice cream 
after it has been partially frozen. As it begins to appear 
thick, the freezer is stopped and the crushed fruit added. 
At this stage, the ice cream is not so stiff that the fruit 
cannot be properly mixed with it and there is little or no 
danger of coagulating the cream. 



PREPARING THE MIX. FILLERS AND BINDERS 145 

2. The extract flavorings are used largely in commercial 
ice-cream making, chiefly because they are easily obtained, 
relatively cheap, and can be stored without spoiling. 
Some ice-cream makers claim that some of these extract 
flavorings impart disagreeable flavors to the ice cream. So 
far as the authors' experience goes, this claim cannot be 
substantiated. The poorer grades of extracts should never 




Fig. 32. — The IMiller ice cream mixer. 

be used. Supply houses keep several grades, and the best 
grade of flavoring extracts should invariably be added to 
the cream. The amount of flavoring extract to be used 
depends upon the degree of concentration of the extract. 
If the best extract is secured, one ounce to one gallon of 
cream or two small tablespoonfuls for every gallon of cream 
used is about the proper amount. The extract should 
ordinarily not be added until just previous to putting the 
mix into the freezing can. Especially is this important 



146 DAIRY TECHNOLOGY 

when the cream is pasteurized. Pasteurization is likely 
to drive off the extract flavors. These are mostly volatile. 
Some of the oil-flavorings are not so volatile, and it does 
not matter when they are added. 

3. The quantity of sugar used in making plain ice cream 
is usually one pound of sugar to six of cream. The sugar 
should be of the best granulated variety and must be 
thoroughly dissolved before freezing. 

" Salt^ is not usually added to ice cream, purposely, at 
least; but careful and repeated tastings by many people 
proved that the unbiased consumer prefers a cream con- 
taining salt at the rate of half a teaspoonful per gallon of 
mixture to a cream which is not thus modified. The taste 
of the salt as such does not become evident until a much 
larger quantity is used." 

Fillers and Binders. — The purpose of using fillers in 
ice-cream making is to give the product a firmer body with 
better standing up qualities. Fillers do not necessarily 
increase the swell and may even lessen it when large quan- 
tities of such materials are used. 

Of the starchy fillers that may be used, rice flour, wheat 
flour and cornstarch give the best results, because of the 
smallness of their starch grains. Cornstarch is the least 
desirable. Starchy fillers must be thoroughly cooked be- 
fore being added to the cream. If this is not done the 
starch grains can readily be detected when the product is 
eaten. This is undesirable in a high-grade product. 

Condensed milk is being used to a great extent in ice- 
cream making, and with very satisfactory results. Some 
large factories have their own condensing machinery, by 
means of which they not only make their own filler, but 
convert any surplus milk into a product that may be 

1 Vermont Bui. 155. 



PREPARING THE MIX. FILLERS AND BINDERS 147 

stored until needed in their factory or disposed of through 
other channels. Plain evaporated milk in bulk is the grade 
of condensed milk commonly used for this purpose. 

Egg fillers usually are not used in low-grade ice cream 
because they are expensive. In order that eggs may have 
the desired effect upon the body of the ice cream, they 
should be cooked. This is done by mixing the beaten eggs 
with milk or cream, then cooking it, so that it forms a thin 
custard. Such a custard, when added to thin cream and 
frozen, does not increase in volume so much as does a 
normal rich cream. 

Rennet is sometimes used in ice-cream making, but has 
little or no effect unless the milk or cream be warm when the 
rennet is added in order that curdling may take place. 
Under these conditions the product shows a slightly 
smoother texture and firmer body. Rennet is seldom used 
in commercial ice-cream making. 

Milk powder is used for ice cream both as filler, binder, 
and batch. 

The chief functions of binders in ice cream are to bind 
the materials into one homogeneous mass, and prevent 
water crystals from forming after the ice cream has stood 
a day or more. Ice cream containing a binder or filler 
does not melt readily when served. 

One of the fillers most widely used for this purpose is 
gelatin. This substance is prepared for use by dissolving 
it In hot skim milk or water, and stirring quickly into the 
cream. The manufacturer must carefully select the gelatin 
in order to be sure that it is perfectly pure and sanitary. 
According to Washburn^ the higher-priced gelatin is cheaper 
in the end than the low-priced goods. He states that 
three and a half to four pounds of high-grade gelatin, cost- 
^ Vermont Bid, iSv 



148 DAIRY TECHNOLOGY 

ing about a dollar, will produce the same results as will six 
to eight pounds of a cheaper grade costing 50 per cent more. 

At the present time gelatin is being replaced to some 
extent by gum tragacanth. One reason for this change is 
that many people and some health ofhcers object to the use 
of gelatin. They claim that it may be dangerous to health, 
because it may have come from diseased animals, or it 
may have been contaminated before or during the manu- 
facturing process. Gum tragacanth is perfectly odorless 
and is very satisfactory as a binder, even in very small 
quantities. Stock may be made up as follows: "Dissolve 
I ounce of gum in i quart of hot water; add 3 pounds 
granulated sugar and mix thoroughly. This will produce 
about one and one half quarts of gum tragacanth stock. 
One quart of this stock is commonly used in making ten 
gallons of ice cream." 

Tragacanth ^ is the gummy exudation from plants be- 
longing to the genus Astragalus, family Leguminosas. The 
gum is in ribbon-shaped bands, i to 3 mm. thick, long and 
linear, straight or spirally twisted. 

" Indian gum" ^ has its origin in other plants and is 
usually found in lumps, never in ribbon-shaped bands. 

Because of this difference in physical characteristics, 
adulteration of tragacanth with the cheaper Indian gum 
is probably not attempted. But large quantities of gum 
are sold in the pulverized form in which no physical dif- 
ference can be detected. It has been found ^ that Indian 
gmn has a volatile acidity 7I times as great as that of 
tragacanth. Or expressed as acetic acid, Indian gum 
contains about 15.8 per cent acetic acid and tragacanth, 
2.1 per cent acetic acid. 

^ U. S. Pharmacopoeia. ^ u. S. Dept. of Agr., Bui. Chem. Cir. 94. 

^ U. S. Dept. of Agr., Bui, Chem. Cir. 94. 



PREPARING THE MIX. FILLERS AND BINDERS 149 

Gelatin, gum tragacanth and other binders are pre- 
pared with sugar and sold under various commercial 
names. Powdered arrow root, sago, Iceland moss, gly- 
cerine, etc., are occasionally used in ice-cream making, 
but have no great commercial importance. 

Ice cream that is to be used in soda water must con- 
tain sufficient binder to prevent it from being broken up 
and dissolved by the jet of soda. Cream made especially 
for fountain use frequently is of lower fat content and 
higher gum or gelatin content than the product made 
for the regular trade. 

Most ice-cream manufacturers use some one of the many 
prepared binders or fillers. These latter are usually ob- 
tained in powder form. A certain amount of this powder 
is thoroughly mixed with the dry granulated sugar. Then 
some cream is added and the whole stirred to form a thick 
paste. By first mixing the sugar and filler the danger of 
lumping is much lessened. More cream is gradually 
added to the sugary paste until a uniform emulsion is 
formed. This is then strained into the definite amount 
of cream to be frozen. The whole is thoroughly mixed 
and at once put into the freezing can. About five and 
one-half gallons of mix make ten gallons of ice cream. 

Great care should be taken in preparing the mix not 
to add too much of the filler and binder at the expense of 
butter fat. Too much filler or binder is likely to cause 
a sticky and soggy body. Such ice cream is more like 
flavored tough pudding, and is not reHshed. Ice cream 
of this character is also more likely to coat the inside 
of the mouth of the consumer with a sticky and slimy 
layer. 



CHAPTER XVII. 

FREEZING THE MIX. 

Ice and Salt. — Having held the cream at about 34° F., 
for from 12 to 24 hours, and having added the sugar, 
flavoring and binder, we are ready to strain and freeze 
the mixture. 

A freezing mixture is made of ice and salt. The chief 
cause of the freezing is the attraction of salt for water. 
This causes the ice to melt rapidly and absorb heat. 
Whenever a frozen solid is reduced to a liquid, heat is 
absorbed, and when one pound of ice melts to water at 
32° F., it absorbs 144 British Thermal Units (one B.T.U. 
being the heat given up by i pound of water in cooling 
1° F.). This heat is absorbed, to a great extent, from 
the cream mixture in the freezing can, and finally the 
temperature is reduced below the freezing point. 

Cream may be frozen by packing the mixture of ice 
and salt directly around the freezing can, or by making a 
brine in a separate receptacle and circulating the brine 
around the freezing can. 

On a small scale the tub freezer is commonly employed, 
and the ice to be used should be finely crushed in order 
to expose to the salt the greatest possible amount of sur- 
face, and insure rapid freezing. When large chunks are 
put into the freezer, they do not pack close, large air 
spaces are formed, and the ice can not so well perform its 
function of extracting the heat from the cream. Further- 
more, large pieces of ice are likely to jam and dent the 

150 



FREEZING THE MIX 151 

freezing can. It is almost impossible to pound out a 
dent and make the surface as smooth as it was originally. 

Ground rock salt is used in preference to the line salt, 
because the former can be mixed more uniformly through 
the crushed ice, and does not dissolve too rapidly. Fine 
salt dissolves almost immicdiately, causes the pieces of 
ice to freeze together into chunks, and does not form so 
uniform a freezing mixture as does the crushed rock 
salt. 

One part of salt mixed with about twelve parts of ice 
will freeze the cream in about the proper length of time, and 
give general satisfaction, but the amount must be varied to 
suit conditions. The maker needs to use his judgment in 
this respect. 

Ice and salt are sometimes mixed on the floor in a manner 
similar to that of mixing feed, but this practice has two 
objectionable features: first, a great deal of the ice will 
melt before it can be used, thus causing a needless waste 
of ice; and secondly, just as great a quantity of salt will 
be put into the bottom of the tub as on top, thus causing 
a needless waste of salt. 

There is httle or no necessity for putting salt into the 
bottom of the tub, because the salt above is being washed 
down by the melted ice. No salt need be added until 
the freezing tub has been half filled with ice. At this 
point a portion of the salt should be added, and then re- 
latively greater proportions added as the tub is filled. 
Crushed ice, free from salt, may be first added, then 
the mixture of crushed ice and salt. In this manner the 
ice and salt may be mixed together in a box or on the floor. 

The chief objection to the use of too much salt, aside 
from the needless expense, is that an excess of salt causes 
the cream to freeze too rapidly. This rapid freezing is 



152 DAIRY TECHNOLOGY 

likely to cause a grainy texture and a low overrun. A 
lack of sufficient salt causes smeary ice cream. Lumps of 
butter are also likely to form. 

In the winter, when the freezer is in a very cold room, 
it is sometimes noticed that an unusually long time is 
required to freeze the cream. This is undoubtedly due to 
the low surrounding temperature retarding the melting 
of the ice. When the melting is delayed, the absorption 
of heat from the cream is delayed and, therefore, the 
freezing process is retarded. In the cold room the ice 
around the freezer does not melt and form brine rapidly; 
hence, heat can be conducted from the cream only at 
points where the ice particles are against the can, and 
this is but a relatively small proportion of the entire area 
of the can. When brine is formed, it is in contact with 
the entire surface of the freezing can, and hence conducts 
the heat from the cream more rapidly. 

To overcome this slow formation of brine, it is recom- 
mended that some water be poured over the ice and salt 
mixture. Having the ice crushed into very fine pieces 
will also aid in overcoming this difficulty. 

In the style of freezers in which the brine system is 
employed, the same general principles apply. The mix- 
ture of ice and salt must be in the proper proportion to 
produce a brine of such temperature that the cream will 
be frozen in the proper length of time to insure good qual- 
ity of ice cream. Under average conditions a mixture of 
one part of salt to fifteen of ice will .produce a brine of 
about 10° F., and will do satisfactory work in the freezer. 
Many brine freezers are provided with a compartment for 
this purpose, and the brine circulated by means of a pump 
driven by the shaft that drives the freezer. Factories 
equipped with artificial refrigeration commonly have a large, 



FREEZING THE MIX 1 53 

well-insulated tank, and the brine is kept cold by a coil of 
ammonia pipes. 

Speed of Dasher. — The speed of the dasher must be 
such that the cream will be uniformly frozen, and be well 
whipped during the freezing process. If the cream is put 
into the freezer at a temperature under 40° F., it will be 
quickly frozen, and the freezer should be run at its maximum 
speed during the entire time. If the temperature of the 
cream is 50° F. or above, in order to avoid churning, the 
freezer should be run at slow speed at first, until the mix 
is brought down close to the freezing point; then the 
machine can be brought to full speed and the freezing 
completed. If it is impossible to run the freezer at low 
speed, then, intermittent freezing may be practiced. If 
this latter is resorted to, no salt should be added, at first, to 
the ice around the freezing can. The mixing of salt would 
cause the can to freeze fast, and the part of the cream next 
to the can would freeze solid, thus forming icy cream. 

In the vertical batch freezers, the dasher commonly 
makes 90 to 100 revolutions per minute, and the can, re- 
volving in the opposite direction, makes the same number 
of revolutions, the result being equivalent to from 180 to 
200 revolutions per minute. 

Freezing Period. — The time required for freezing is 
dependent upon (i) the temperature of the mix when put 
into the freezer, (2) the freezing mixture (size of pieces 
of ice and proportion of salt), and (3), to a Hmited extent, 
the composition of the mix. The composition and spe- 
cific gravity of the mix are nearly constant for the same 
class of product, so that the maker must depend upon 
regulating the two other factors to control the duration of 
the freezing period. This latter cannot be varied widely 
without impairing the texture of the product. 



154 DAIRY TECHNOLOGY 

A prolonged freezing period may be due to (i) insuffi- 
cient salt, (2) coarse ice, and (3) warm mix. The result 
may be a greasy ice cream, perhaps containing granules 
of butter; this latter is very objectionable to the con- 
sumer. 

Rapid freezing of the cream is due chiefly to an excess 
of salt, or to very finely crushed ice, well packed around 
the can. 

The result of too rapid freezing is a coarse, granular 
texture, the ice cream frequently containing small crys- 
tals of clear ice. 

When cream is put into the freezer at a temperature 
of 40° F., or less, the proper texture and swell will be 
secured by allowing 10 to 14 minutes for the freezing proc- 
ess. If the cream is 15° to 20° F. warmer than this, an 
additional five minutes should be allowed for the freezing. 
When cream, at 60° F., is frozen in eight minutes, it passes 
through the whipping stage so quickly that insufficient 
swell will be obtained, and the texture is likely to be coarse 
and granular. 

Freezing Point. — The freezing point of ice cream, 
as commonly made commercially, is not a very variable 
factor; but when fruit ice cream and the various ices are 
made, the addition of the fruit and the extra sugar re- 
quired lowers the freezing point. The freezing point of 
sherbets, water ices etc., is 5° to 8° lower than that of 
ice cream. A little colder freezing mixture and a lower 
storing temperature are necessary for these products. 

The freezing point of the cream is not affected, mate- 
rially, by the fat content, nor by the presence of fillers or 
binders; but all of these make the cream appear more firm 
at a given temperature than cream in which these things 
are lacking. 



FREEZING THE MIX 155 

Eflfect of the Sugar Content on the Freezing Point. ^ — 

" Sugar goes into true solution and has a low molecular 
weight as compared to egg or gelatine. It lowers the 
freezing point very materially, and uniformly, in pro- 
portion to its presence. Similarly the milk sugar, a nor- 
mal milk constituent, being in true solution, causes milk 
to freeze at a lower temperature than does pure water. 
Ice cream sweetened to average taste contains approxi- 
mately 14 per cent added sugar, and has a freezing point 
of about 28^° F. When ice cream has frozen to the proper 
consistency for removing from the freezer to the packers, 
its temperature is about 28° to 27° F. The following 
table, prepared from the data obtained at this station, 
using a Beckmann's freezing-point thermometer graduated 
in -Y'oo" of a degree, may be of interest as showing the 
freezing points of different sugar solutions. 



Material. 


Observed 
freezing point. 


Plain skim milk 


3i03°F. 
30.40° F. 
29.7o°F. 
28.6o°F. 
27.07°F. " 


5 per cent solution sugar in skim milk 

10 per cent solution sugar in skim milk 

14 per cent solution sugar in skim milk 

25 per cent solution sugar in skim milk 



Swell. — • The volume of ice cream obtained in excess of 
the amount of total mix put into the freezer constitutes 
the " swell " or overrun. This increase in volume is due 
almost wholly to the incorporation of air into the product 
and, therefore, can scarcely be called an overrun. Noth- 
ing of a tangible character is added during the freezing 
process. 

The more viscous the cream is, the greater the swell 
that may be secured, because the viscous cream is able 
to retain the air that is beaten into it. 

The amount of swell is influenced by the rate of freezing. 
^ Vermont Bui. No. 155. 



156 DAIRY TECHNOLOGY 

When cream is frozen very quickly, less swell is secured. 
The reason for this seems to be that the swell is produced 
only while the cream is passing through a few degrees of 
temperature just before it freezes. Only during this short 
time is it sufhciently viscous to retain the air that is beaten 
into it. According to Washburn/ when the temperature 
of the cream reaches 34° F., the cream begins to foam up 
and continues to increase in volume until a temperature 
of 29° or 28° F. is reached. At this point the temperature 
remains constant for from four to fifteen minutes. During 
this time the latent heat is being extracted from the cream 
by the freezing mixture. The swelling of the cream, that 
begins at about 34° F., is most rapid toward the end of 
this period of lowering temperature. Just before the cream 
freezes, the swell is very rapid. 

The effect upon the swell, of over-freezing, is reported 
by the same authority. A series of trials was made in a 
double-disc continuous freezer, run at the rate of 225 
revolutions per minute. It was found that when the ice 
cream was drawn off at a temperature of 29° F., the swell 
was 70 per cent; at 28° F., 60 per cent; at 27° F., 50 per 
cent; at 26° F., 43 per cent; at 25° F., 40 per cent. The 
ice cream drawn off at 29° F. was too soft, but that at 28° 
was entirely satisfactory. 

The speed of the rotator or beater also influences the 
overrun or swell. Some freezers have facilities for varying 
the speed, making it slow at first, then during the latter 
part of the freezing period increasing the speed. The 
higher the speed up to a certain limit (250 rev. per min.), 
the more air is beaten into the ice cream. High speed 
during the first part of the freezing period may cause the 
cream to churn. 

1 Vermont Bui. 155. 



FREEZING THE MIX 1 57 

Stopping Point. — When frozen to the consistency of 
thick syrup the ice cream is dipped or poured out into pack- 
ing cans, which have been previously iced. Care should 
be exercised in the transfer to avoid expelling the in- 
corporated air. When the ice cream is put into packing 
cans that are not standing in ice, the relatively warm can 
melts some of the cream. This, when refrozen, is coarse 
and icy. Where hardening rooms are used, this is avoided 
by placing the packing cans in the hardening room for a 
while before filling. Twelve to twenty-four hours after 
being frozen the ice cream will be found to have a better 
and more uniform flavor because of the blending of the 
several flavors into one. 

Hardening. — To prepare ice cream for delivery, it 
must be thoroughly hardened. This can be accompHshed 
only by lowering the temperature of the product to from 
14° to 17° F. The hardening may be done in the packing 
tubs that are used for dehvery, setting the cans of ice 
cream in a tank of brine or in a room cooled by artificial 
refrigeration. 

Just before being sent from the factory, the ice cream 
must be re-iced. The space around the can should be well 
filled, and the top well covered with the ice and salt mix- 
ture before the ice cream is shipped. Some manufacturers 
cover the can and tub with a blanket and finally with a 
neatly fitting oil cloth. 

Returned Goods. — It is a good rule never to allow 
melted ice cream to be returned to the factory; but at 
times this cannot be avoided. A total loss may be pre- 
vented by churning such melted ice cream. Butter made 
from such cream makes satisfactory cooking butter. The 
melted ice cream should be mixed with skim milk and re- 
skimmcd on a separator; a starter should then be added to 
the cream and the whole ripened and then churned as usual. 



158 DAIRY TECHNOLOGY 

If the melted cream is of good flavor and fresh, it may 
be refrozen. 

Fancy Ice Cream. — The most common of the fancy ice 
cream is brick, made up of several layers. These bricks are 
usually made up of three differently colored layers. Red, 
white and chocolate are common colors. The molds are 
of various sizes, such as one pint, one quart, etc. The molds 
are also of two kinds, those having a loose cover, both on 
top and bottom, and those having only the top cover loose. 

Small or individual molds are also manufactured rep- 
resenting fruits, animals, soldiers, etc. Ice-cream molds 
of this kind are in demand especially for children's parties. 
If cream is colored in this connection it should imitate as 
nearly as possible the object it is supposed to represent. 

To make the layer ice cream, about one-third of the 
mold is filled, say, with white ice cream. This is smoothed 
on the surface, then another third of the mold is filled with 
chocolate or dark-colored ice cream. This is smoothed off, 
and finally the last third of the mold is filled with the red 
ice cream. This is leveled off even with the top edge of the 
mold and the cover put on. Sometimes a sheet of paraffined 
paper is laid on the top of the ice cream before the cover 
is put on. This is perhaps most desirable when the mold 
is old and loose around the edge. 

When the mold is filled and the cover is on, tie string 
around the mold to hold the cover tight. 

Place the mold at once in a freezing temperature. This 
maybe on shelves in a hardening room, or in a mixture of 
crushed ice and salt. If the latter, the mixture should 
rest on a perforated board to allow the brine to drain 
through into a lower jacket. The brine is cold and should 
be retained in the cooling tank or box. The box should 
be provided with a cover. 



FREEZING THE MIX 159 

Allow the molds to remain here long enough to freeze 
solid. The hard frozen ice cream can be removed from 
the mold by dipping the mold and contents into cold water, 
and by wiping the mold on the outside with a dry towel. 
The ice cream may also be loosened from the mold by using 
a case knife around the edges. 

Fat Content of Different Portions. — Some ice-cream 
dealers claim that ice cream which has stood in a packer 
for a week shows a differently distributed fat content than 
at the beginning of the week. This observed difference 
in the fat content in the dift'erent parts of the ice cream is 
evidently due to the rising of the fat, through the partially 
melted ice cream, and in some cases to the alternate freez- 
ing and thawing, crowding a large per cent of the solids 
toward the center. 

Washburn^ has found that the fat in semi-melted ice 
cream rises somewhat. He tested portions of a can of ice 
cream that had stood for one week in a mellow condition, 
and found that the top portion of cream contained 28 per 
cent fat, the middle 15 per cent and the bottom five per 
cent. The same authority states that gelatine and gum 
tragacanth had but little effect in preventing this rise of 
fat. Fruit ice creams separated more quickly than the 
plain flavors, due to the heavy fruit and rich syrup. 
However, when the cream was properly hardened, and 
held in that condition, the fat content of the different 
parts did not change. 

^ Vermont Bui. 155. 



CHAPTER XVIII. 

FORMULAS. 

Vanilla Ice Cream. — Formulas for ice cream may be 
obtained from various sources, and are of infinitely great 
variety. A standard vanilla ice cream that gives general 
satisfaction is made as follows: 

45 pounds i8-per-cent cream. 
8 pounds sugar. 
4 ounces vanilla extract. 
4 ounces gelatine. 

This will make ten gallons of ice cream testing 15.1 
per cent fat. One of the commercially sold fillers may be 
substituted for the gelatine. These should be used accord- 
ing to directions and according to body desired in the ice 
cream. 

This vanilla ice cream may be used as a stock cream for 
making small batches of other flavors. For instance, if 
a small quantity of chocolate ice cream is desired, it can 
be made by taking out the required amount of vanilla ice 
cream (mix) and adding the chocolate syrup to it. 

Nut ice creams are commonly made by exactly the 
same formula as the vanilla, except for the addition of 
nuts. The nuts should not be added until the cream is 
partly frozen. This prevents settling of the added nuts. 

Any ice cream in which a syrup or liquid flavoring is 

used may be made from the above formula, but, in some 

instances, more sugar will be necessary and the vanilla 

will be omitted. 

160 



FORMULAS l6l 

Fruit Ice Cream. — Nothing is more justly popular than 
fruit ice cream in which the fresh fruit is used — especially 
strawberry or peach. To make lo gallons of strawberry 
ice cream: 

45 pounds i8-per-cent cream. 
8 pounds sugar. 

I gallon crushed strawberries (sweetened). 
4 ounces gelatine. 

In adding fruit of any kind to any mixture containing 
milk and cream it is usually best to add it after the cream 
has been partly frozen. If added sooner the heavier 
fruit is likely to settle, and the acid in the juice is likely 
to cause some coagulation. 

Parfait.^ 

4 gallons 30-per-cent cream. 

Yolks of 10 dozen eggs (stirred and beaten). 

14 pounds sugar. 

4 ounces vanilla extract. 

4 pounds ground walnut meats (or other nuts). 

Mousse.^ 

2 gallons 30-per-cent cream (whipped). 

4 pounds sugar. 

I quart cranberry juice (or other fruit or nuts). 

1 pints lemon juice. 

Lacto.2 

6 gallons sour skim milk or buttermilk. 
18 pounds sugar. 

2 dozen eggs (yolks and whites beaten separately) 

2 quarts cherry juice or cherry syrup (or other fruit). 

3 pints lemon juice. 

^ Iowa Bui. 123. 2 loyja Bui. 118. 



l62 DAIRY TECHNOLOGY 

Sherbet. 

6 gallons water or milk. 

6 quarts orange juice (or other fruit). 

1 pint lemon juice. 

2 dozen eggs, whites only. 
23 pounds sugar. 

Another recipe for a very delicious and rich sherbet, 
especially useful when made on a small scale, is as follows : 

I quart of water. 

I pound of sugar. 

I quart of fresh strawberries. 

Whites of six eggs. 

Juice of two lemons. 

Boil sugar and water together to make the syrup. Pick 
over the strawberries and thoroughly mash them; then 
add the lemon juice and mix. When the syrup has been 
cooled, pour it over the mashed berries, mix and strain 
into the freezing can, and freeze. When about half frozen 
add the beaten whites of eggs and complete freezing. 



CHAPTER XIX. 

ICE-CREAM MACHINERY. 

The great growth of the ice cream industry has naturally 
been accompanied and aided by the invention of various 




Fig. ;j^. — Da\as milk-can drip saver. 

pieces of machinery especially adapted to the needs of 
the ice-cream maker. 

163 



164 



DAIRY TECHNOLOGY 



For the storage or holding of cream the small factory 
may employ common milk cans, but in the large factory, 
vats are necessary, and these may be ordinary jacketed 
tin vats or enameled iron tanks. The last mentioned are 
perfectly sanitary and easily cleaned, being lined with a 
thin coating of enamel, perfectly smooth and without a 




Fig. 34. — Sweet cream storage rooms. (Ice Cream Trade Journal.) 



seam or crack. A vat having cooling facilities attached 
is preferred, unless it be placed in a refrigerator room. 

When pasteurization is practiced, the machines used 
are the same as those made for use in the creamery or 
city milk plant. 

The ice-cream mixer is used, when large quantities of 
material are handled at one time, to secure a perfectly 
uniform mix. This machine is invariably a cooler as 
well as a mixer. One general style having a horizontal 



ICE-CREAM MACHINERY 



165 



stirring device through which ice water or cold brine 
may be pumped, resembles many styles of cream ripeners 
commonly used in butter factories. Another style is the 
vertical mixer, having an upright dasher for a stirring device 
and a jacket for the circulation of ice water. This is similar 
in general make up to the starter can of the butter factory. 

Freezers. — Ice-cream freezers are of many styles and 
designs, but may be classified under the following heads: 

I. Batch Ice-cream Freezer 
or Tub Freezer, in which the 
freezing can is set into a wooden 
tub and the ice and salt packed 
around it. This is the old style 
freezer, the simplest and most 
primitive in construction and 
mechanism. Of this style are 
the small household freezers 
and also many power machines 
used in small factories. There 
are probably more freezers of 
this kind in use than all other 
kinds together. However, they 
are not adaptable to ice-cream 
making on a large scale; hence, 
in the large factory, machines 
of a more improved design are 
usually employed. The gear wheels of the power tub 
freezers are so arranged that the can is revolved in one 
direction and the dasher in the opposite direction at the 
same speed. In many of the hand freezers the dasher is 
stationary, and the can is not geared high, so it is difficult 
to attain sufficient speed on the crank to properly beat the 
cream during freezing. 




Fig. 35. — The Little Giant 
ice-cream freezer. 



i66 



DAIRY TECHNOLOGY 




Fig. 36. — The ISIiller horizontal ice-cream freezer. 




■■J^ 



Fig. 37. — C. P. disc ice-cream freezer. 



ICE-CREAM MACHINERY 



167 



2. The Batch Brine Freezer Is of two varieties, the ver- 
tical and the horizontal. In these freezers instead of 
packing ice around the freezing can, brine is made in 
a separate compartment and pumped through a jacket 




Fig. 38. — Improved Model D brine freezer. 



surrounding the freezing can, circulating from end to end 
in order to freeze uniformly. The batch freezers are used 
in freezing products in which fruits of various kinds and 
beaten eggs are added after the mix is partly frozen. 
3. The Continuous Brine Freezer is a machine permitting 



i68 



DAIRY TECHNOLOGY 



the unfrozen mix to enter continuously at one end and the 
frozen product continuously to run out at the other end. 
A common form of these continuous freezers is the disk 
freezer consisting of two oblong tanks, side by side. In 
each tank are several revolving, hollow disks on a hollow 
shaft through which the brine for freezing is pumped. 

The cream flows into the first tank or freezing compart- 
ment from the supply reservoir on to the revolving disks 




Fig. 39. — The Creasy ice breaker. 

and the freezing process begins. At the far end of this 
tank the partly frozen mixture overflows into the second 
compartment and passes along over the freezing disks. 
(The smaller freezers have but one compartment.) In 
this compartment, just above the disks, is a screw that 
carries away the frozen cream and discharges it into the 
packing cans. The top of each freezing compartment is 
provided with a plate-glass cover, so that the cream is in 
view during the entire freezing process. 



ICE-CREAM MACHINERY 



169 



Ice Crusher. — This is a great labor-saving device and 
is indispensable where large quantities of ice are crushed. 
The machine breaks the ice into pieces of a more uniformly 
small size than can possibly be done by hand with an ax or 
stomper. 

Homogenizer. — This is one of the latest inventions in 
ice-cream machinery. As its name indicates, it is a ma- 




FiG. 40. — A six-cylinder Progress homogenizer. 

chine for converting liquids such as cream into a homo- 
geneous mass. This is accomplished by breaking the fat 
globules into such line particles that they are unable to 
rise to the surface, but remain incorporated in the liquid. 
The machine consists of a pump or a series of pumps which 
discharge the liquid against the homogenizing valve. 
This latter may be compared to a safety valve which blows 
off at a pressure of from 2000 to 3000 pounds per square 
inch. The valve disk is made of agate and closes per- 



170 



DAIRY TECHNOLOGY 



fectly into the seat. When the pressure from the pump 
is sufficient, the valve is forced open, but the space be- 
tween the disk and the seat is so small that when the fat 




Fig. 41. — The Honey cone machine. 



globules are forced through they are separated into tiny 
particles. 

The homogenizer is and has been used for manufacturing 
cream from skim milk and butter. Some have even gone 
so far as to make the skim milk from milk powder and mixed 
it with unsalted storage or fresh butter. Finished prod- 
ucts made and offered for sale in this manner must be 



ICE-CREAM MACfflNERY 



171 



labeled as such. This process makes the problem of getting 
sweet cream less difficult. 

Sanitary Pipes and Fittings. — The only kind of pipes 
that should be used for transmitting cream and milk are 
the so-called sanitary pipes. The piping is perfectly smooth 
and heavily tinned. It is in short lengths and put together 
in a manner similar to that of connecting fire hose, so that 
the pipes may all be taken apart and cleaned very readily. 

Ice-cream Can Washer. — This machine finds a place in 
large factories where a great many packing cans are used. 




Fig. 42. — Fort Atkinson ice-cream can washer. 

It is a contrivance in which brushes and jets of water and 
steam are used to cleanse and sterilize the cans in much the 
same way that bottles and cans are cleaned and sterilized 
in a city milk plant. 

Packing Cans. — These are of great importance from a 
sanitary standpoint, because the ice cream remains in 
them often for several days. There should be no crevices 
or rough spots in the can and no exposed iron. Heavily 
tinned cans are extensively used, but enameled iron ones 
are better, being smoother, more easily and perfectly 
cleaned and hence more sanitary. 



172 DAIRY TECHNOLOGY 

Sterilizer, — A large steam sterilizer is essential for a 
factory turning out a strictly sanitary product. Here all 
the freezing and packing cans and utensils used in handling 
the materials can be made perfectly sterile daily. 

Many small utensils too numerous to mention are needed 
in the ice-cream factory. 



CHAPTER XX. 

ICE-CREAM FACTORIES. 

Local Creameries. — The farmers' co-operative cream- 
ery of to-day is in keen competition with private enter- 
prises that as a rule have a much larger working fund than 
the local creameries. These private enterprises are usually 
managed by better business methods, are better located 




Fig. 43. — View of Collins Bros.' ice-cream freezing room. 
(Ice Cream Trade Journal.) 

in relation to the markets, and, in most cases, are doing 
business on a larger scale than the local creamery plant. 
It therefore behooves the local creamery to adopt modern 
business methods, to cater to the markets and to find the 
most profitable method of disposing of their products. 

173 



174 DAIRY TECHNOLOGY 

The farmers' local creameries, on the other hand, have 
the advantages of having easier access to a large supply of 
fresh sweet cream at a minimum cost. These local cream- 
eries have the building and much of the costly machinery, 
such as engine, boiler, vats, etc., the initial expense of which 
does not need to be charged up against the ice-cream 
department. They also sustain a minimum loss on any 
surplus cream. In case that the ice-cream consumption 
is diminished, as is usually the case during cold weather, 
large city ice-cream manufacturers often lose money on 
their sweet cream. The creamery can turn this surplus 
cream into butter with scarcely any loss. 

Since the price of butter is always low in summer, at 
the time when production is greatest, any method of con- 
verting the raw material at this time into a higher priced 
product would seem to be worthy of our consideration. 
The manufacture of ice cream has been tried and proven 
successful in the creamery. 

Advantages. — The chief advantages of ice-cream making 
as a side line in local creameries are as follows: 

1. The profits from this product are materially greater 
than those obtainable from butter during the summer. 

2. The creamery is already equipped with steam, ice, 
power and a suitable building for the manufacture of ice 
cream. 

3. The local creamery is in a position to secure fresh 
sweet cream direct from the producer. 

4. The local creamery can supply its own and neighbor- 
ing towns with this product with greater ease and efficiency 
than can a large factory in a distant city. 

As in starting any new line of business, it must be taken 
up on a small scale to begin with. A suitable market must 
be found for the product. Some creameries are so located 



I 



ICE-CREAM FACTORIES 1 75 

that they could not profitably take up this side line, but 
such conditions are rarely found. In many small towns 
ice cream is a rare delicacy, but when it is easily available 
the people soon acquire the ice-cream habit and consume 
large quantities of it, thus increasing the demand. 

Cost of Equipment. — The machinery for making ice 
cream on a small scale need not be extensive or costly. 
Just as good a product can be made in the simple tub 
freezer as can be made in the most complex freezer on 
the market. 

The machinery absolutely necessary for the manu- 
facture of 60 to 500 gallons of ice cream per week would 
cost about as follows: 

I lo-gal. tub freezer $80.00 to $110.00 

I ice crusher 150 to 50 . 00 

1 pulley and 24 ft. of 4-in. belting 10.00 to 20.00 

4 to 40 large packers or 8 to 80 small ones ... 30 . 00 to 400 . 00 

2 to 20 lo-gal. cream cans or a vat 4 50 to 50.00 

Ice tools, ice-cream utensils, etc 10.00 to 20.00 

Total $136 . 00 to $650 . 00 

One hundred and fifty dollars will buy the necessary 
equipment for a creamery that is starting the manufacture 
of ice cream in a locality where the demand is small. 

Profits from this Product. — The cost of making one 
gallon of ice cream may be calculated as follows: The 
creamery buys fat in sweet cream at 3 cents above the 
market quotation for butter. Let us assume that the 
average quotation during the summer is 25 cents per 
pound. 

Cents. 
4.7 lbs. i8-per-cent cream at 28 cents per pound of fat ... . 23 . 7 

xV lb. sugar 6.0 

Flavoring and binder i . o 

Ice and labor ^.^ 

34-0 



176 DAIRY TECHNOLOGY 

This ice cream that costs 34 cents per gallon to make, 
sells at 80 cents per gallon. The fat content of the above 
gallon of ice cream is .846 pound. The materials other 
than the cream cost 10.3 cents; hence 69.7 cents was 
received for the .846 pomid of fat, or 82.4 cents per pound. 

This pound of fat would have made about 1.2 pounds of 
butter which, at 25 cents per pound, would have brought 
30 cents. This shows a difference of 52.4 cents per pound 
of fat in favor of ice-cream making. Making allowance 
for possible losses on ice cream, this product should, under 
favorable conditions, net about twice as much per pound 
of fat as butter. This cost will vary under different con- 
ditions. 

Many local creameries have made ice cream during 
the past few summers and have made a success of this 
side line; they have been able to pay the farmers more 
for their cream than factories not making ice cream, 
and they have been better able to compete successfully 
with large private enterprises. 

The Large City Factory. — Under the above-described 
conditions, ice cream can be made with a minimum out- 
lay of money. The amount of machinery may be greatly 
increased to facilitate the handhng of larger quantities 
of material. In some of the big ice-cream factories of 
the cities there is a large investment, both in building and 
equipments. 

Owing to difficulties in securing an ample supply of 
fresh cream most large factories have installed homoge- 
nizers, and, especially during the summer, make homoge- 
nized cream from butter and milk. 

Homogenized Cream. — Milk is received each morning 
direct from the farms. Each can is inspected and, if 
found fresh and clean, is accepted and emptied into the 



ICE-CREAM FACTORIES 



177 



receiving vat. From here it runs through a pasteurizer, 
then over a cooler which brings it to a temperature of 
34° to 38° F., thence to huge holding vats in a refriger- 
ated room, where it is held until needed. 

In another cold room is found sweet, unsalted butter, 
stored at a temperature of about 10° below zero Fahren- 
heit. This is usually secured by contract from whole milk 




i'lG. 44. — Sweet cream receivers in Collins Bros.' factory. 



creameries, and is of very good quahty being "June extras'' 
and "Fall extras." 

To prepare the materials for the freezer, butter and 
milk are placed in proper proportions in a mixing vat, 
heated to about 140° F., and agitated to form an emulsion, 
then passed through the homogenizer. The emulsion issues 
from this machine as a homogeneous cream, thoroughly 
pasteurized and with the fat thoroughly and permanently 



178 DAIRY TECHNOLOGY 

incorporated in the serum. The flavor of this cream, 
however, is not so fine as that of the fresh, natural prod- 
uct. Upon leaving the homogenizer, the cream is cooled 
nearly to the freezing point and pumped back into hold- 
ing vats in the cold room just as is done with the milk. 

In such a factory as this, operating on so large a scale, 
the difficulty of securing a sufficient quantity of fresh 
sweet cream can easily be comprehended. The advantage 
of using homogenized cream made from butter and milk 
is very evident. In addition to this, the homogenized 
cream is very viscous and can be used immediately, 
while ordinary pasteurized cream must be held at a low 
temperature for about a day in order to regain its vis- 
cosity. It would be very inconvenient and, in some in- 
stances, difficult to hold in storage such vast quantities of 
cream. 

Making the Mix. — The cream is drawn from the 
storage vats as wanted, a definite quantity being placed 
in a mixing vat where the sugar, flavor, and binder are 
added, exact quantities being weighed in. These mix-i 
tures are dissolved and thoroughly mixed with the cream f 
by means of an agitating device. The mixer is also a 
cooler, brine being pumped through the agitator. 

Freezing and Hardening. — The mix being made, it 
is piped to the supply tanks of the freezers. Near these 
tanks are several freezers, some continuous and some 
batch brine freezers. During the rush season these ma- 
chines are busy turning out their frozen dehcacy for twelve 
or more hours per day. As soon as a packing can is full, 
a sheet of parchment paper is placed over the top, then 
the metal cover is put on, and the can is put into the hard- 
ening room, a room held at about the zero point, being 
cooled by artificial refrigeration. Here the cans remain 



ICE-CREAM FACTORIES 



179 



for about twenty-four hours until the cream is thoroughly- 
hardened all through and until taken out for shipment. 

To prepare the cream for shipping, the cans are placed 
in a tub and packed with salt and ice. 

Artificial refrigeration is employed for all the cooling, 




Fig. 45. — Ice-cream hardening room in Wheat's factory. 

using the direct expansion in the storage and hardening 
rooms, and brine for the cooling coils and freezers. The 
factory makes all its own artificial ice used in the packing 
cans for shipment. 
In one style of hardening room, the cans are placed 



l8o DAIRY TECHNOLOGY 

upon shelves where small streams of brine play upon 
them. The brine drains to certain points, is pumped back 
to the tank, recooled and circulated again. Or the cans 
may be placed in tanks of brine until the cream hardens. 
Either style makes a more or less sloppy hardening room, 
and although the cooling is very efficient, these styles are 
not being used so widely as the dry hardening room. 

A hardening room which employs the dry system is 
cooled by ammonia expansion coils. A uniform tempera- 
ture is maintained and the rapidity of the hardening in- 
creased by continuous air currents generated by electric 
fans. 

Standardization of Cream. — This topic is treated under 
" City Milk Supply," but some modifications are necessary 
when materials other than milk and cream are used. It 
must be remembered that the sugar, flavoring, etc., added 
to the cream have similar effects in reducing the percentage 
of fat as has the addition of skim milk. Therefore, if we 
add 8 pounds of sugar to 45 pounds of cream containing 
20 per cent fat, the sweetened cream will contain a con- 
siderably smaller percentage of fat. 45 pounds of 20- 
per-cent cream contain 9 pounds of fat; then 53 pounds 
(45 -|- 8 = 53) of the sweetened cream contain 9 divided 
by 53 times 100, which ec|uals 17 per cent fat. Using the 
formula 45 pounds of cream, 8 pounds of sugar, 4 ounces 
of flavoring extract, 4 ounces gelatine, to make a lo-gallon 
batch of ice cream, if the maker wishes his finished product 
to contain 14 per cent fat, what per cent of fat should he 
have in his cream? The total weight of materials is 45 
pounds of cream plus 8 pounds sugar, plus | ounce flavor 
extract plus | ounce gelatine. This equals 53.5 pounds. 
If the per cent of fat is 14, or the minimum law standard, 
this amount of ice cream mix contains 7.49 pounds of 



ICE-CREAM FACTORIES l8l 

butter fat. Then the 45 pounds of cream must contain 
7.49 pounds of fat or (7.49 divided by 45 times 100) 16.6 
per cent of fat. 

Every ice-cream factory should standardize the cream. 
The range between the minimum per cent of fat (usually 
specified by law) and the maximum per cent of fat de- 
sirable is rather narrow. 



CHAPTER XXI. 

SCORING ICE CREAM. 

Proposed Score Cards. — There are two or more score 
cards being used tentatively in judging ice cream. One 
of them is as follows : ^ 

Flavor 45 

Body 20 

Texture 20 

Permanency 10 

Package 5 

Total 100 

Flavor. To be that of clean, sweet cream sweetened to 
taste with cane sugar; the score to be cut for any flavor 
of sour cream and cut severely for any dirty flavor, and 
but little if too sweet or not sweet enough, or if the added 
flavor is too high or too low, for these are largely regulated 
by trade demands. 

Body. To be firm, mellow and slightly elastic under 
pressure of the finger at a temperature of 18° F., or less. 
It must not be rubbery or too weak. 

Texture. To be smooth, creamy and free from coarse 
water crystals; the score to be cut moderately if too coarse, 
and severely if inclined to be sticky or doughy. 

Permanency. To have a reasonable standing-up power 
on an ordinarily cool dish, and to offer some resistance in 
the mouth, instead of melting and disappearing as Hquid 
almost immediately upon being tasted. 

^ Vermont Bui. 155. 
182 



SCORING ICE CREAM 183 

Package. To be clean, tidy and free from evidence of 
slovenly workmanship. 
Another proposed score card is as follows:^ 

Flavor 45 

Texture 25 

Richness 15 

Appearance 10 

Color S 

Total 100 

I. Flavor. 

Definition of Good Ice-cream Flavor. 
The cream flavor must be clean and creamy, and com- 
bined with flavoring material which blends with the cream 
to a full and delicious flavor. 

Defects in Flavor. 

1. Defects due to the use of flavors which will not blend 
with the other ingredients. 

2. Defects due to cream used: 
Sour-cream flavor. 
Old-cream flavor. 
Bitter-cream flavor. 
Metallic-cream flavor. 
Oily-cream flavor. 
Weedy-cream flavor. 

Barn flavor. 

Unclean flavor. 

Burned or overheated flavor. 

3. Defects in flavor due to filler used: 
Condensed-milk flavor. 

Starch flavor. 
Gum flavor. 
Gelatine flavor. 

^ Iowa Bui. 123. 



1 84 DAIRY TECHNOLOGY 

4. Defects in flavor due to other ingredients: 
Too sweet. 
Lack of sweetness. 

Coarse flavor due to flavoring material. 
Stale-fruit flavor. 
Rancid-nut flavor. 
Mouldy-nut flavor. 

II. Texture: 

Definition of a Good Texture. 
The cream must be firmly frozen and be smooth and 
velvety. 

Dejects in Texture. 

Icy. This defect is most noticeable toward the bottom 
of the container and may be due to improper packing or 
by holding too long ice cream which was manufactured 
without filler. 

Coarse. This defect may be due to the use of too thin 
cream or to packing while too soft. 

Sticky. This is due to fillers such as gelatine, sweetened 
condensed milk, glucose, etc. 

Buttery. This defect is due to the use of cream which 
has been partially churned before freezing, or to cream 
which enters the freezer at too high a temperature. It 
may also be due to operating the freezer at too high speed 
or to some defect in the construction of the freezer. 

Too Soft. Due to improper packing after freezing. 

When judging cream containing nuts, fruits, etc., due al- 
lowance should be made for the presence of such ingredients. 

III. Richness : 

Ice cream containing the amount of butter fat required 
by the state pure-food law should be considered perfect 
in richness. 



SCORING ICE CREAM 185 

The richness is determined by making chemical analysis 
for fat. 

IV. Appearance : 

Ice cream scoring perfect in appearance should be clean 
and neatly put up and in a clean container. 

Defects. Cream of unclean appearance; lack of parch- 
ment circle over ice cream; dirty container; rusty con- 
tainer; dirty ice-cream tub; old tag strings attached to 
handle of tub. 

When judging brick ice cream special attention should 
be given to the uniformity of the layers, to the neat fold- 
ing of the parchment wrapper and to cleanliness and general 
appearance of the package. 

V. Color: 

Ice cream of perfect color is such as contains only the 
natural color imparted to it by the flavoring materials 
used. If color is added it should harmonize with the par- 
ticular flavoring used. 

Defects in Color. Too high color; unnatural color such 
as colors different from the color of the natural flavoring 
material used. 

Individual molds, if colored, should be as nearly as 
possible the same color as the object they represent. 



CHAPTER XXII. 

ICE-CREAM STANDARDS. 

At the present time there is considerable agitation 
in the ice-cream world over the pure-food standards that 
relate to the composition of ice cream. Undoubtedly, 
the most important part of the laws pertaining to the 
manufacture of ice cream is that requiring that the prod- 
uct shall be made under sanitary conditions and shall 
contain nothing deleterious to health. This portion of 
the present laws is generally satisfactory to every one. 

Binders and Fillers. — In some states and cities there 
are laws or ordinances providing for a fat standard and 
regulating the kind and amount of filler or binder used. 
The large city ice-cream manufacturers as a whole are 
opposed to standards. In regard to binders it may be 
said that, providing the binder is a healthful substance, 
there should be no ruling against it by any pure-food law. 
Gelatine and gum tragacanth are used in ice cream to give 
it a smooth texture and prevent granulation and crystalli- 
zation of the watery parts while in storage, and there 
seems to be no good reason for classing them as adulter- 
ants. But the use of corn starch, rice and wheat flour, 
and other fillers to hide a lack of butter fat must be con- 
demned, when the product is sold under the name of ice 
cream. Large am.ounts of fillers are seldom used when 
the fat standard is enforced. 

Fat Standard. — The fat content of ice cream is a much- 
discussed subject. The justice of a fat standard seems 

1 86 



ICE-CREAM STANDARDS 1 87 

to depend upon whether the consumer, the people as a 
whole, consider ice cream to be frozen cream, or merely 
a frozen delicacy with a creamy consistency. Many 
ice-cream manufacturers maintain that the latter is the 
case, and that there is no more necessity for a fat standard 
for ice cream than there is for a fat standard for cream 
gravy or creamed potatoes. They claim that since the 
product is not necessarily purchased because of its food 
value, there should be no standard for the amount of 
nutrients contained therein. But if the first-mentioned 
definition holds, then the fat standard for ice cream is 
perfectly just and legitimate. However, under any con- 
ditions, it seems hardly fair to the consumer or to the 
manufacturers to sell a product containing 7 per cent 
of butter fat under the same name as that containing 
14 per cent of butter fat. 

If another material (milk) is used in the manufacture 
of a frozen product, an appropriate name should distin- 
guish it from other frozen products, just as the name 
" Water Ice " is used to distinguish that product from ice 
cream. A frozen product made of milk can be manu- 
factured and sold at a much lower cost than that made 
of cream. Such a product could be called " Ice Milk." 
The consumer might then obtain a cheap refreshment at 
a proper price; and he may also, if he desires, obtain a 
product of higher quality and be certain of getting it by 
paying the higher price for the richer product, properly 
called ice cream. 

In South Dakota, the 14-per-cent fat standard is being 
enforced. Several cases were brought to the attention 
of the dairy inspection department in which some facto- 
ries located in large cities were selling so-called ice cream 
at a very low price. This product contained from 6 to 



1 88 DAIRY TECHNOLOGY 

lo per cent of butter fat. The local and small ice-cream 
factory made a product containing 14 per cent of fat. It 
was impossible for this latter factory to compete with 
the other factories manufacturing the inferior article. 
The product shipped in from the large plant contained from 
6 to 10 per cent of fat, and contained an excess of filler. 
A good product can thus easily be driven from the market 
by a cheap substitute. It is apparently proper that 
there should be a law to protect the consumers as well as 
those who desire to place a superior article on the market. 
Under a proper classification these two products would 
have been sold under different names and would not have 
come into such sharp competition with each other. 

The increasing magnitude of the ice-cream industry 
makes necessary the adoption of appropriate trade names 
for all the various ices. Several classifications, varying in 
complexity, have been proposed. This may be taken as 
an indication of a general desire to establish well-defined 
classes of frozen products, and it seems eminently fitting to 
make a distinction in name between the products made of 
milk and those made of cream. 

Testing Ice Cream. — The presence of sugar, gelatine 
and gum in ice cream makes necessary some modifica- 
tion of the Babcock Test in order to secure good results. 

The following method is suggested; it is comparatively 
simple and produces a very clear reading. 

I. The Hydrocliloric and Acetic-acid MctJiod. — Nine 
grams of the sample are weighed into the test bottle 
and 30 cubic centimeters of a mixture of equal parts 
by volume of concentrated hydrochloric acid and 80 per 
cent acetic acid are added. Mix thoroughly and heat 
on the water bath till the mixture darkens, but avoid 
charring. Whirl in the centrifuge, add hot water as 



ICE-CREAM STANDARDS 189 

in the regular testing and read the percentage of fat 
directly. 

If charring has interfered with the fat reading, add 
ether after whirling to dissolve the fat, and draw off the 
ether solution into another bottle. Evaporate off the 
ether, fill with hot water and again whirl and read. This 
latter method should not be resorted to except in cases 
of necessity. It is always better to run the test over, 
provided there is enough left of the original sample. 

2. Modified Bahcock Method. — Ice cream can be tested 
successfully by using sulphuric acid, provided certain pre- 
cautions are observed. The writers have obtained good 
results by using the following method. Alelt the sample 
slowly at a low temperature to a creamy consistency; 
quickly weigh 9 grams of it into a milk bottle. Add about 
twelve cubic centimeters soft water, mix, then succes- 
sively add small quantities of sulphuric acid, mix and let 
stand to permit the acid to act. The action of the acid 
is indicated by the color of the mixture, and when this 
assumes a strong coffee color the reaction has gone far 
enough and no more acid is required. If the color con- 
tinues to darken, add a small quantity of soft water to 
prevent charring. 

Bacteria in Ice Cream. — The subject of bacteria in ice 
cream has received attention only during the past few 
years. There is a popular belief that, because cream is 
frozen, it cannot decompose and that the organisms origi- 
nally in the cream are either killed or rendered harmless 
by the continued low temperature. However, experiments 
show that bacteria do remain virile and that certain types 
even proliferate at sub-freezing temperatures. The bac- 
terial content of ice cream, then, is a matter of importance 
from a hygienic standpoint. 



igo DAIRY TECHNOLOGY 

We have previously noted that the conditions of the milk 
and cream supply in many localities are far from ideal. 
Since milk and cream are the main constituents of ice 
cream, this latter product cannot be of any better quality 
than the materials of which it is made. However, all 
methods of improving milk and cream are just as applicable 
to the ice-cream industry as to city milk supply. 

Investigations of conditions in Washington, D. C, re- 
ported in Bulletin 56 of the Hygienic Laboratory, show 
that, in 1907, in 130 samples of cream examined, the average 
number of bacteria per cubic centimeter was 12,130,080. 
At the same time, 381 samples of milk were subjected to 
a bacteriological examination and the average number of 
organisms per cubic centimeter was 3,415,533. Samples 
of ice cream at the same time contained from 100,000 to 
400,000,000 bacteria per cubic centimeter. 

Dr. George W. Stiles of Washington, D. C, investigated 
the bacterial flora of ice cream in cold storage, and secured 
the following results: 

Four samples of ice cream were secured from different 
dealers and placed in storage at a temperature varying from 
0° to 10° F. The bacterial content of these samples aver- 
aged on the 

Per c.c. 

Initial count 70,000,000 

3rd day ■. 1 20,000,000 

6th day 65,000,000 

Qth day 80,000,000 

nth day 50,000,000 

14th day 13,000,000 

17th day 21,000,000 

20th day 85,000,000 

23rd day 90,000,000 

27th day 225,000,000 

30th day 22,000,000 

34th day 13,000,000 



ICE-CREAM STANDARDS 191 

Just what significance should be attached to these bac- 
terial counts depends chiefly upon the types or kinds of 
organisms that are present in the ice cream. Certain 
varieties may produce toxins, while others are harmless. 

Cases are on record where ice cream caused digestive 
derangements, headache, diarrhea and symptoms of 
poisoning soon after the eating. Such cases of illness are 
commonly explained as ptomaine poisoning and are usually 
due to unsanitary conditions of the raw material (cream, 
gelatine, etc.), the ice-cream factory, or prolonged storage 
of the ice cream. 

The owners of one large ice-cream factory guarantee 
their product sold to be absolutely free from tubercle 
bacilli, and other disease-producing bacteria, and to contain 
no more than 25,000 germs per cubic centimeter when 
deUvered to the consumer. At this particular plant a bac- 
terial count is made of all the cream to be frozen. Separate 
counts are made (i) of the cream after homogenization, (2) 
of the mix before freezing and (3) of the frozen product 
ready for shipment. The counts run, on an average, about 
as follows: cream, 2000 bacteria per cubic centimeter; 
mix, 12,000 per cubic centimeter, and ice cream 24,000 
per cubic centimeter. The ice cream is also tested for 
gas-producing organisms, any bacteria of the B. Coli 
type being considered a very objectionable contamination. 
The analysis report card used in this work is as follows: 



192 DAIRY TECHNOLOGY 

BACTERIOLOGICAL ANALYSIS OF ICE CREAM.i 

Ice cream examined 

No. of Plates used for each dilution 

Average number of Bacteria in dilution i- 100 Per c.c 

" " " " I- 1,000 

" I- s,ooo 

" I- 10,000 

" " " " 1-100,000 

Total average of Bacteria 

Gas % C02 % H2. . . .% B. Coli Communis 

Date cream made 19 . . 

Date of analysis 19 . . 

Date plates ' 'counted' ' 19 . . Signed 

Bacteriologist. 
1 Collins Bros., Chicago, 111. 



CHAPTER XXIII. 

MECHANIC.\L REFRIGERATION. 

Mechanical refrigeration has been considered expensive 
and impracticable on a small scale until within a few years. 
The science of producing cold artificially has been simphfied 
and reduced to such a practical basis that it is now used in 
many large as well as small plants where formerly natural 
ice was used altogether. The chief factors affecting the 
cost of mechanical refrigeration may be said to be similar 
to those affecting the economic running of the remaining 
machinery, such as kind of fuel used, skill of fireman, style 
and condition of boiler, proportion of boiler power to work 
done, upon the correlative size of all machinery, upon 
kind of insulation and care of cooHng-rooms and upon 
efficiency of compressor and whole refrigerating system. 

Chemicals Used. — The most common substances used 
in mechanical refrigeration are ammonia and carbonic 
acid. A number of others are in use, but from a creamery 
standpoint these only are of importance. Ammonia is 
used chiefly. It is efficient, cheap, and not so dangerous 
to life and property as are some of the others. Anhydrous 
ammonia has a boiling-point of 27° below zero at atmos- 
pheric pressure. The latent heat of ammonia is also 
great. Ammonia has great chemical stabiHty and is not 
explosive in nature. Ammonia attacks copper and brass, 
but has no effect upon iron and steel pipes. 

If ammonia should escape through a leak into a room, 
the operator can protect himself from the effects of the 
gas by breathing through a wet sponge held in the mouth. 

193 



194 DAIRY TECHNOLOGY 

Ammonia leaks may be detected by holding a glass rod 
dipped in hydrochloric acid to the places where the leaks 
are suspected. When ammonia comes in contact with 
hydrochloric acid, white fumes are formed. 

Principles of Producing Cold Artificially. — The chief 
principle involved in producing artilicial cold is that when 
a substance passes from a liquid into a gaseous state, a 
definite amount of latent heat is absorbed. When water 
in a kettle on the stove begins to boil and passes off 
into steam, no higher temperature can be reached. No 
matter how much heat is applied under those same condi- 
tions, the temperature remains the same. This extra heat 
is used in transforming the water into steam. If this 
steam were confined, and that heat removed by cooling, 
the steam would again pass into a hquid state. We are 
familiar with the coolness produced by rapid evaporation 
of perspiration from the body. Mechanical refrigeration 
is virtually a process of evaporation of the cooling medium 
during which heat is absorbed; and then again liquefying 
the cooling medium by compression and cooling to remove 
the absorbed heat. To increase the abihty of the cooling 
medium to absorb heat the cooling medium is compressed 
and liquefied. So we might say that any compression 
refrigerating system has three separate operations necessary 
to form the complete cycle of mechanical refrigeration, 

viz. : 

1. Compression of the ammonia gas. 

2. Condensation of the ammonia gas. 

3. Expansion of the ammonia gas. 

I. The machine which causes the compression of the 
ammonia gas is called the compressor. In construction 
it is much like a steam engine. Small machines are single 
but large machines are double acting. Gas is drawn in 



MECHANICAL REFRIGERATION 195 

on the suction stroke, compressed and discharged on the 
return stroke. The pressure generated varies between 
120 and 175 pounds per square inch. During the com- 
pression, heat is developed in proportion to pressure ex- 
erted. The greater the pressure, the higher the tempera- 
ture of the gas. Part of the heat of compression is carried 
off by means of a continuous stream of water running 
through a jacket around the cyhnder. 

2. From the compressor the gas is forced through the 
pipes into the condensing coils, in which the warm com- 
pressed gas is cooled still more. When sufficient heat 
has been removed from this gas, it assumes a liquid con- 
dition and is ready to expand into a gaseous form for the 
purpose of absorbing heat and producing cold. During 
the cooling and condensing processes each pound of ammo- 
nia parts with about five hundred and sixty units of heat, 
which amount can again be absorbed when it expands 
into gas at the lower pressure. 

3. This liquefied gas, which is still under great pressure, 
is then admitted through what is termed the expansion 
valve. This valve is especially constructed for that pur- 
pose, and has only a very minute opening in it for the 
admission of the liquid ammonia. On the expansion side 
the pressure is low (20 to 30 pounds). As the liquid ammo- 
nia emerges from the high-pressure side through the ex- 
pansion valve into the expansion side it forms a gas. 
This expanded gas may then be circulated through coils 
for cooling purposes. From there it passes back into the 
suction side of the compressor ready to go through another 
similar cycle. 

From the above description it will be seen that there 
are two sides to the system, the expansion side and the 
compression side. The compression side extends from 



196 DAIRY TECHNOLOGY 

the compressor to the expansion valve; the expansion 
side from the expansion valve to the suction side of the 
compressor, inclusive. 

Transferring the Cold. — The methods of transferring 
the cold to the different places in the building vary. There 
are two systems: 

1. Direct Expansion. 

2. Brine System. 

1. By the direct-expansion system the condensing 
pipes of the system are extended to the room or place 
at which the cooling is to be done. An extended set of 
expansion coils then conveys the gas which absorbs the 
heat. A lower temperature can be produced by this 
method than with the brine system. 

2. In the brine system a large brine tank is placed 
somewhere in the creamery or ice-cream plant at a place 
most convenient with respect to cooling. This tank con- 
tains a strong solution of brine. The chief reason why 
brine is used in preference to water is that brine has a 
very low freezing-point. This varies with different de- 
grees of saturation. 

Either sodium chloride (common salt) or calcium chlo- 
ride may be used for brine. The latter is considered best 
chiefly because it is not so hard on the pipes, and it keeps 
the brine pipes cleaner than does a salt brine. The follow- 
ing tables give properties of brine made from these two 
substances. 

The expansion coils pass through the brine tank and 
cool the brine. Special pumps force the cold brine through 
pipes to the cooling room, cream vat, cooling coils, ice- 
cream freezer, etc. 



MECHANICAL REFRIGERATION 



197 



SHOWING PROPERTIES OF SOLUTION OF SALT. (Siebly.) 
(Chloride of Sodium.) 



Per 

cent of 


Pounds 
salt per 


Degrees 
on salom- 


Weight 
per gallon 
at 39° F. 


Specific 

gravity at 


Specific 


Freez- 
ing- 


Freezing- 
point 
Celsius. 


salt by 
weight. 


gallon of 
solution. 


eter 
60° F. 


39° F. 

4°C. 


heat. 


point 
Fahr. 


I 


0.084 


4 


8.40 


1.007 


0.992 


30-5 


-0.8 


2 


0.169 


8 


8 


46 


i.ois 


0.984 


29-5 


-i-s 


2-5 


0.212 


10 


8 


SO 


1. 019 


0.980 


28.6 


-1-9 


3 


0.256 


12 


8 


53 


1.023 


0.976 


27.8 


-2.3 


3-5 


0.300 


14 


8 


56 


1.026 


0.972 


27.1 


-2.7 


4 


0.344 


16 


8 


59 


1.030 


0.968 


26.6 


-3-0 


5 


0-433 


20 


8 


65 


1-037 


0.960 


25.2 


-3-8 


6 


0.523 


24 


8 


72 


I -045 


0.946 


23-9 


-4-5 


7 


0.617 


28 


8 


78 


1-053 


0.932 


22.5 


-5-3 


8 


0.708 


32 


8 


85 


1 .061 


0.919 


21.2 


-6.0 


9 


0.802 


36 


8 


91 


1.068 


0.905 


19.9 


-6.7 


10 


0.897 


40 


8 


97 


1 .076 


0.892 


18.7 


-7-4 


12 


1 .092 


48 


9 


10 


1 .091 


0.874 


16.0 


-8.9 


IS 


1.389 


60 


9 


26 


1. 115 


0.855 


12.2 


— II .0 


20 


1.928 


80 


9 


64 


I -155 


0.829 


6.1 


-14.4 


24 


2.376 


q6 


9 


90 


1. 187 


0.795 


1 . 2 


-17. 1 


25 


2.488 


100 


9 


97 


1 . 196 


0.783 


0-5 


-17.8 


26 


2.610 


104 


10 


04 


1 .204 


0.771 


— I.I 


-18.4 



PROPERTIES OF SOLUTION OF CHLORIDE OF CALCIUM. 

(Siebly.) 



Per cent by 


Specific heat. 


Specific gravity 


Freezing-point in 


Freezing-point in 


weight. 


at 60° Fahr. 


degrees Fahr. 


degrees Cels. 


I 


0.996 


I .oog 


31 


-0.5 


5 


0.964 


1-043 


27-5 


-2.5 


10 


0.896 


1.087 


22 


-5-6 


15 


0.860 


I - 134 


15 


-9.6 


20 


0.834 


1. 182 


5 


-14.8 


25 


0.790 


1-234 


-8 


— 22. 1 



Use of Brine. — For all general cooling purposes, the 
brine system is more economical and satisfactory because 
the brine may be kept cold by running the compressor 
just a few hours each day. The cold is stored and used 



198 DAIRY TECHNOLOGY 

when wanted. In the direct-expansion system, as soon 
as the compressor stops refrigeration ceases. However, 
for dry hardening rooms the direct-expansion system is 
absolutely necessary to secure and maintain a sufficiently 
low temperature. 

Strength of Brine. — The proper degree of concentra- 
tion of the salt solution depends upon the temperature 
desired. Low temperatures demand a stronger brine to pre- 
vent freezing; but an unnecessarily strong brine is undesir- 
able, because the stronger the brine is, the less is its specific 
heat; that is, it has less ability to absorb heat, and too 
concentrated brine is likely to clog the pipes. 

Size of Compressor. — The size of a refrigeration ma- 
chine is expressed as a certain number of tons' capacity. 
For instance a machine of four tons' capacity means that 
that machine would produce in 24 hours as much cold as 
is given off by four tons of ice melting to water at 32° F. 
Its actual ice-making capacity is about half this much; 
a four-ton machine will make about 2 tons of ice per day. 

In selecting the size of machine needed it must be 
remembered that the capacity is rated on a 24-hour run. 
If conditions are such that it will be desirable to run the 
compressor only four hours per day then the machine must 
have six times the daily capacity needed. The larger 
machines produce a ton of refrigeration at less cost than 
small ones, but in a general way, for small and medium- 
sized machines, the power required is about two and one- 
quarter horse power per ton of refrigeration. 

Operation of an Ammonia Plant. — Charging and operat- 
ing an ammonia plant are very ably discussed by H. H. 
Kelley in The Engineer, from which the following is taken. 

" When about to start an ice or refrigerating plant, the 
first thing necessary is to see that the system is charged 



MECHANICAL REFRIGERATION 199 

with the proper amount of ammonia. Before the ammonia 
is put in, however, all air and moisture must be removed; 
otherwise the efhciency of the system will be seriously 
interfered with. Special valves are usually provided for 
discharging the air, which is removed from the system 
by starting the compressor and pumping the air out, the 
operation of gas cylinder being just the reverse of that when 
it is working ammonia gas. It is practically impossible 
to get all the air out of the entire system by this means, 
so that some other course must be taken to remove any 
remaining air after the compressor has been started at 
regular work. This can be accomplished by admitting 
the ammonia a little at a time, permitting the air to escape 
through a purge valve, the air being thus expelled by dis- 
placement. The cylinder containing the anhydrous am- 
monia is connected to the charging valve by a suitable 
pipe, and the valve opened. The compressor is then kept 
running slowly with the suction and discharge valves wide 
open and the expansion valve closed. When one cylinder 
is emptied put another in its place, being careful to close 
the charging valve before attempting to remove the empty 
cylinder, opening it when the fresh cylinder is connected 
up. 

'' From sixty to seventy-five per cent of the full charge 
is sufficient to start with so that the air may have an op- 
portunity of escaping with as httle loss of ammonia as 
possible. An additional quantity of ammonia may then 
be put in each day until the full charge has been introduced. 
When the ammonia cylinders have been emptied and a 
charge of, say, seventy-five per cent of the full amount 
has been introduced, the charging valve is closed and the 
expansion valve opened. The glass gauge on the ammonia 
receiver will indicate the depth of ammonia. The appear- 
ance of frost on the pipe leading to the coils and the cooling 
of the brine in the tank will indicate that enough ammonia 
has been introduced to start with. It is sometimes difficult 
to completely empty an ammonia cylinder without first 
applying heat. The process of cooling being the same 
when the ammonia expands from the cylinder into the 



200 DAIRY TECHNOLOGY 

system as when leaving the expansion valve, a low temper- 
ature is produced and the cylinder and connections be- 
come covered with frost. When this occurs the cylinder 
must be slightly warmed in order to be able to get all the 
ammonia out of it. The ammonia c}linders, when filled, 
should never be subjected to rough handling and are 
preferably kept in a cool place free from any liability 
to accident. The fact that ammonia is soluble in water 
should be well understood by persons charging a refrigerat- 
ing system, or working about the plant. One part of water 
will absorb about 800 parts of ammonia gas and in case of 
accident to the ammonia piping or machine, water should 
be emplo}'ed to absorb the escaping gas. Persons em- 
ployed about a plant of this kind should be provided with 
some style of respirator, the simplest form of which is a 
wet cloth held over the mouth and nose. 

" After starting the compressor at the proper speed 
and adjusting the regulating \-alve note the temperature of 
the delivery pipe, and if there is a tendency to heat, open 
it wider, and vice versa. This valve should be carefully 
regulated until the temperature of the delivery pipe is 
practically the same as the water discharged from the 
ammonia condenser. With too light a charge of ammonia 
the dehvery pipe will become heated even when the regulat- 
ing valve is wide open. As a general thing when the plant 
is working properly the temperature of the refrigerator is 
about 15° lower than the brine being used, the temperature 
of the water discharged from the ammonia condenser will 
be about 15° lower than that of the condenser, the pointers 
on the gauges will vibrate the same distance at each stroke 
of the compressor and the frost on the pipes entering and 
leaving the refrigerator will be about the same. B}' placing 
the ear close to the expansion valve the ammonia can be 
heard passing through it, the sound being uniform and 
continuous when everything is working properly. 

" When air is present the flow of ammonia will be more 
or less intermittent, which irregularity is generally notice- 
able through a change in the usual sound heard at the 
expansion valve. The pressure in the condenser will also 



MECHANICAL REFRIGERATION 20I 

be higher and the effect of the apparatus as a whole will 
be changed, and, of course, not so good. These changes 
will be quickly noticed by a person accustomed to the con- 
ditions obtaining when everything is in order and working 
properly. 

" The presence of oil or water in the system is generally 
detected by shocks occurring in the compressor cylinder. 

** In nearly all plants the presence of oil in the system 
of piping is unavoidable. The oil used for lubricating 
purposes, especially at the piston rod stuffing boxes, works 
into the cylinders and is carried with the hot gas into the 
ammonia piping, where it never fails to cause trouble. 
The method of removing the air from the system has al- 
ready been referred to, but the removal of oil is accomplished 
by means of an oil separator. This is placed in the main 
pipe between the compressor and the condenser, and is 
of about the size of the ammonia receiver. Sometimes 
another oil separator is placed in the return pipe close to 
the compressor which serves to eliminate any remaining 
oil in the warmer gas and to remove pieces of scale and 
other foreign matter which, if permitted to enter the com- 
pressor cyhnder, would tend to destroy it in a very short 
time. 

" The oil, which always gets into the system sooner or 
later and in greater or less quantity, depending upon the 
care exercised to avoid it, acts as an insulator and pre- 
vents the rapid transfer of heat from the ammonia to 
the pipe, and also occupies considerable space that is re- 
quired for the ammonia where the best results are to be 
obtained." 

Insulation. — Where mechanical refrigeration is used the 
insulation of cooHng rooms, brine tank and pipes is of great 
importance from an economic point of view. 

The insulating material must be a non-absorbent of 
moisture, a poor conductor of heat, and of sufficient strength 
and durability to remain for many years without crumbling 
or decomposing. 



202 DAIRY TECHNOLOGY 

All ammonia and brine pipes passing through rooms 
where refrigeration is not desired should be covered with 
insulation two inches thick for temperatures of zero or 
: below, and one to one and a half inches for higher 
temperatures. 

According to the H. W. Johns-Mansfield Co., there is a 
loss of nine tons of refrigeration on account of radiation in 
24 hours on 500 feet of 3|-inch brine pipe with temperature 
of zero and outside temperature of 70° F. Figuring the 
cost of refrigeration at 50 cents per ton, the loss would be 
$4.50 per day of 24 hours. 



PART IV. 

BY-PRODUCTS OF THE CREAMERY 
AND CHEESE FACTORY. 

CHAPTER XXIV. 

COTTAGE CHEESE. 

Cottage Cheese. — Cottage cheese (Dutch cheese, or 
Schmier-kase) is a product that usually finds a ready sale 
on the market at a price that insures a good profit to the 
manufacturer. Especially is this true in large cities and 
in mining districts during hot weather. 

In the past this product was made mostly in the home, 
and varied greatly in quality and general characteristics. 
But at the present time, large quantities of it are being 
manufactured in whole milk creameries, large dairies, etc. 
In order that a manufacturer may turn out a uniform 
product, a definite method of manufacture should be fol- 
lowed. The process admits of a number of variations in 
its details, hence judgment must be used by the manufac- 
turer in adopting the process most suitable to his particular 
conditions, kind of raw material, and market demands. 

Milk to Use. — In making cottage cheese, just as in 
all other dairy products, it is essential to have a fresh, 
clean, pure raw material to start with. Undesirable odors 
and flavors in the milk seriously affect the finished product. 

Skim milk rather than whole milk is used in cottage- 
cheese making, because in the use of whole milk a large 
percentage of the fat is lost in the whey. If a rich, creamy 

203 



204 DAIRY TECHNOLOGY 

cheese is desired, it can be secured more economically by 
using skim milk, and then adding cream to the finished 
product. 

A good quality of cottage cheese can be manufactured 
from good buttermilk. Skim milk and buttermilk together 
may be used in various proportions. 

Use of Starters. — In order to insure a uniform product 
the fermentation must be controlled, and to do this, a 
pure culture of lactic-acid bacteria is important. These 
cultures, or "starters" as they are commonly called, are 
used extensively in butter and cheese making, and may be 
secured from various manufacturers. Directions for their 
use accompany each package, or ma}' be found in the 
various texts on butter and cheese making. 

A better control of the fermentation can be secured by 
using pasteurized milk than by using raw milk, but in 
either case a good starter should be used to insure a uni- 
form and desirable flavor in the cheese. 

Souring the Milk. — The common method of making 
cottage cheese is to sour the skim milk by a lactic acid 
fermentation, rather than by the addition of commercial 
acid. The fermentation of the skim milk may be carried 
on in milk cans or in a vat, depending upon the quantity. 
The milk is warmed to about 70° F., and sufficient starter 
added to insure the coagulation of the milk at the desired 
time. If the milk is pasteurized, a small percentage of 
starter is sufficient; but with raw milk, a larger percentage, 
20 to 25 per cent, of starter, will be better able to over- 
come any undesirable ferments that may be present. This 
will cause the milk to curdle in a much shorter time. 

When a firm curd has been formed it is broken up by 
cutting with cheese knives or stirring with a common 
stirring rod. 



COTTAGE CHEESE 205 

Heating the Curd. — This is a very important process 
and must be done carefully. Heat is applied gradually, 
and the curd stirred continually, but gently, until a tem- 
perature of 96° to 100° F. is reached, which should require 
about thirty minutes for a large vat. This temperature 
is maintained for about twenty minutes, or until the curd 
feels fairly firm and the whey appears clear. 

Different conditions require different temperatures. 
Too low temperatures produce a soft pasty cheese that 
drains with difficulty, and soon develops a high acid flavor. 
Too high temperatures produce a dry, granular and corky 
cheese, for which there is slight demand. 

Draining the Curd. — The common method of drain- 
ing a small quantity of curd is to put it into a cheese-cloth 
bag, and hang it up until all the free whey has run out. 
For large quantities, a fine strainer is more satisfactory. 
This may be of perforated tinware, or a frame or box with 
a bottom made of small meshed wire netting. A piece of 
cheese cloth is placed in the bottom of the strainer and 
the curd poured upon it. Most of the whey quickly runs 
through the cloth. But in order to permit the curd to 
drain thoroughly, it is left on the strainer with occasional 
stirring for about five hours, or until whey ceases to run off. 

Seasoning the Curd. — When the curd is taken from 
the strainer, it is in a single mass. This should be 
thoroughly broken up with a wooden masher or with the 
hands. At this time salt is added in the proportion of 
about one ounce to five pounds of curd. If a rich cheese 
is desired, cream or butter may be added. Too much salt 
causes a dry, granular cheese. In some instances cumin 
or caraway seeds are added. 

Yield of Cheese. — The yield of cottage cheese varies 
somewhat, depending upon its moisture content, the per 



2o6 DAIRY TECHNOLOGY 

cent of casein in the milk and the amount of curd lost in 
the whey. On an average, seven pounds of skim milk 
produce one pound of cottage cheese. 

For retailing this product, the common ice-cream pail 
has been found to be a convenient package. It is cheap, 
sanitary and attractive. The package may be marked 
on the outside to describe suitably its contents. These 
small packages are not sealed air-tight. For this reason 
the cheese should not be put into the retail packages sooner 
than necessary. Cottage cheese may be kept in larger 
bulks in earthen jars. Cottage cheese to be most pala- 
table should be made every other day. 

Use of Rennet in Cottage-cheese Making. — This 
product may be made by curdling the milk with rennet 
instead of with the natural acid. However, in order to 
have the proper flavor, the milk should have an acidity 
of at least j^ per cent when the rennet is added. The 
proportions used are i ounce of rennet to looo pounds of 
milk. Having curdled the milk, the rest of the operation 
is the same as described above. Cheese made in this 
way is apt to be a trifle dry and rubber-like, and mild 
in flavor. 

Use of Hydrochloric Acid. — Much time can be saved 
by adding acid direct to fresh milk instead of waiting 
for it to be developed by fermentation. The milk is 
heated to from 70° to 80° F. Hydrochloric acid (sp. gr. 
1.20) is added at the rate of 10 ounces to 100 pounds of 
milk. This acid is diluted with ten times its bulk of water, 
and added gradually, the milk being stirred constantly. 
The stirring is continued until the curd fully separates, 
leaving a clear whey. Then the whey is drained from 
the curd and the process completed as described above. 
Acid used should be chemically pure, not the commercial. 



COTTAGE CHEESE 207 

Such cheese lacks the pecuhar characteristic flavor of 
that made by lactic fermentation, but this can in a meas- 
ure be restored by the addition of sour cream. 

The average composition of cottage cheese is as follows : ^ 

Per cent. 

Water 73 . i 

Fat 2.8 

Nitrogenous Matter 19.8 

Non-nitrogenous Matter 2.2 

Ash 2.1 

BUTTERMILK CHEESE. 

In past years buttermilk was hardly considered an 
asset in a creamery; but by the manufacture of butter- 
milk cheese, this by-product of butter making may be 
made a source of considerable income. 

Heating the Buttermilk. — As the buttermilk comes 
from the churn it is run into a jacketed vat or can, heated 
to 80° F. and allowed to stand undisturbed for an hour.- 
During this time the buttermilk coagulates, forming a 
soft, flocculent curd. 

The contents of the vat are then heated, with slight 
stirring, to from 130° to 140° F., and again allowed to 
stand undisturbed for an hour. It should be kept close 
to this temperature until placed on the draining rack, 
since the curd drains faster if warm, but it should not 
be re-heated or stirred again before draining. 

In one large creamery where all the buttermilk is manu- 
factured into cheese, the buttermilk is placed in a jacketed 
vat and gradually heated to about 120° F. This heating 
period extends over a period of between 2 and 3 hours. 
The buttermilk is gently stirred at intervals. At the end 

^ Flieschman — The Book of the Dairy. 
2 Bui. No. 211. Wisconsin. 



2o8 DAIRY TECHNOLOGY 

of this period the curd has settled and the whey is drained 
off from the top through gate valves at different heights 
at the end of the vat. 

Draining the Curd. — The vat having stood at a tem- 
perature of 130° to 140° F. for about an hour, the curd 
will have gathered at the bottom of the whey. The next 
step is to transfer this curd with as little whey as possible 
to a draining rack or strainer, such as is used in cottage- 
cheese making. 

If the curd is floating, the whey may be drawn out 
through the vat gate, being passed through the strainer 
to catch the particles of curd it may contain. If the curd 
is at the bottom of the vat then most of the whey may 
be drawn off through a siphon and the thick mass in the 
bottom finally run out into the cloth. Thus, most of the 
whey may be run off, and the curd may be put upon 
the draining rack as a thick mush. If the curd and whey 
are run into the strainer together, much of the curd will 
pass through the cloth with the whey. 

In either case, as soon as all the curd is on the draining 
rack, it is covered and left undisturbed for about twelve 
hours to drain. 

It is very important to have a uniform consistency. 
It will need some manipulation occasionally to prevent 
whey from gathering on the surface or in pockets. 

The curd is sufficiently drained when it can be removed 
from the rack and retain its shape. 

Seasoning the Curd. — The curd, being sufficiently 
drained, is removed from the draining rack, granulated 
or mashed, to break all lumps, then salted and packed. 
Salt is added in the same proportion as in cottage cheese, 
one ounce to about five pounds of cheese. 

Sometimes butter is mixed with the curd. This pro- 



COTTAGE CHEESE 209 

duces a richer cheese, and at times it is sold as Neufscha- 
tel cheese. 

The yield of cheese, the method of marketing, the market 
value, etc., are practically the same as for cottage cheese. 

The main difference in the characteristics of these two 
products is that the buttermilk cheese has a smoother 
texture than the cottage cheese. 

Kind of Buttermilk. — The cheese made from butter- 
milk coming from old, stale, off-flavored cream will retain 
those undesirable qualities. None but the best quality of 
buttermilk should ever be used. 

Sweet buttermilk, or buttermilk having a very low acid 
content, will not curdle on heating; at least a longer time 
is required for coagulation. In making cheese from such 
buttermilk a temperature of between 80° F. and 100° F. 
should be maintained longer. This will permit of the 
development of the lactic-acid-producing bacteria, and 
thereby bring about proper coagulation. 

Pasteurization of the cream does not materially affect 
the quality of buttermilk cheese. However, cream con- 
taining more than 0.4 per cent of acid is likely to curdle 
in very fine grains in the pasteurizer, and it is difficult 
to gather these fme curd particles. Many of these run 
through the strainer cloth with the whey and are lost. 
However, this can be overcome by the addition of some 
skim milk to the buttermilk. The curd from the skim 
milk apparently acts as a sort of a filter. 

For some unexplained reason, buttermilk curd from 
cream containing more than 50 per cent of fat is very 
fine grained and is difficult to collect on the cheese cloth 
strainer, as it runs through the meshes with the whey. 
This also may be overcome by the addition of skim milk 
to the buttermilk. 



2IO DAIRY TECHNOLOGY 

Emphasis should be placed upon the necessity of ob- 
serving closely the different steps in the processes of the 
manufacture of buttermilk cheese. It does not admit of 
the variations that cottage cheese does, because of the fine 
and almost soluble condition of the curd. 

Buttermilk Cream. — Buttermilk cream is made in a 
manner similar to that of making buttermilk cheese; but 
by employing a lower temperature the final product has 
the consistency of thick cream and is quite smooth and 
free from grains or lumps. The only change in the proc- 
ess of manufacture as described above is that instead of 
heating to 130° at the second heating, the curd is heated 
only to 100°. Because of the soft consistency of this 
product it requires a longer time to drain. 

It was found at the Wisconsin Station that this prod- 
uct has a market value. 



CHAPTER XXV. 

WHEY BUTTER. 

In the manufacture of all kinds of cheese whey is a by- 
product. It is commonly returned to the farmers and fed 
to hogs, but in some cases valuable products are recovered 
from it. The composition of whey is fairly constant, 
except that the fat content varies between wide limits. 
The average composition of whey is about as follows: 

Per cent. 

Water 93 • o 

Sugar 5.0 

Albumen 0.7 

Fat 0.3 

Casein 0.3 

Ash 0.7 

The largest percentage of solid matter in whey is milk 
sugar, the recovery of which will be described in a subse- 
quent chapter. 

The solids remaining in whey are sometimes recovered 
by heating or evaporating the water, the residue being 
made into a kind of cheese (mysost). The main constit- 
uent of this cheese is milk sugar, which is in marked con- 
trast to all our common varieties of cheese, the principal 
constituents of which latter are casein and fat. 

The milk solid in the whey that may be most easily re- 
covered is the fat. In cheddar-cheese making the quantity 
of fat left in the whey seldom exceeds 0.3 per cent, and may 
be only one-third this much. In the manufacture of Swiss 
cheese the whey contains from 0.7 to i per cent of fat. 

211 



212 DAIRY TECHNOLOGY 

Hence it was in factories manufacturing this type of 
cheese that whey-butter making originated. 

Original Methods of Making Whey Butter. — Until 
within the present decade, httle attention was paid to 
whey butter. It was manufactured to some extent in 
Swiss cheese factories, but the product was more Uke lard 
chan butter and sold for a low price. 

There were two methods of recovering the fat from the 
whey, the " cold process" and the '' hot process." 

In the former the whey, when drawn from the curd, was 
run into vats or barrels and allowed to stand for 24 hours. 
The "cream" was then skimmed off and churned. This 
method of skimming is not very efficient, as it recovers 
but about two-thirds of the fat. By this process the whey 
cream was very sour, sometimes containing as high as 0.9 
per cent acidity. Hence the resulting butter was of a 
poor quality and had very poor keeping properties. 

In the " hot process" the sweet whey in the kettle was 
heated to a temperature of about 176° F. and stirred con- 
stantly for about half an hour. Soon after the stirring had 
begun, small, white, flocculent pieces of cream appeared 
on the surface. When all the cream had come to the sur- 
face, it was skimmed and dipped off into tubs, and, after 
standing for some time, a considerable quantity of whey 
was drawn off through a hole in the bottom of the tub. 
Even then the remaining cream contained but 12 per cent 
fat. It also contained a quantity of coagulated albumen. 

This method recovered almost as much of the fat as 
can be removed by a centrifugal separator; but the pro- 
longed high temperature is very injurious to the body of 
the butter made from this cream. This cream is sweet 
and pasteurized, and can be made into a fair quahty of 
butter if proper methods are employed. 



WHEY BUTTER 213 

Poor Methods Employed. — The one great reason for 
the poor quality of much of the whey butter at the present 
time as well as in the past is that the cheese makers many 
times spoil the butter in the manufacturing process. The 
whey cream is usually not properly cooled and cared for, 
but is left to cool slowly in the curing room, or is ripened 
at a temperature of 90° F., and churned at a tempera- 
ture as high as 70° F. The resultant product, when such 
methods are employed, is grease rather than butter; and 
because of the high temperatures employed it occasionally 
contains as high as thirty-two per cent water. Some of 
the old Swiss-cheese makers work the butter by taking a 
couple of handfuls of it on a cheese board, sprinkling some 
salt on it, and kneading it as dough is kneaded in bread 
making. 

Because whey butter is usually made on such a small 
scale and is a side line in a cheese factory, it is not 
given sufificient attention to insure a high grade product. 
Many cheese makers have never learned the art of butter 
making, and hence are not quaUfied to turn out a high grade 
of whey butter. 

Modern Whey-butter Making. — That a very high 
quality of butter may be made from whey cream, has 
been demonstrated on numerous occasions. At Brockville 
Exhibition, Ontario, Canada, in 1907, in the butter con- 
test, the exhibit that carried off first prize was whey butter. 
This was in competition with creamery butter. Whey butter 
has been made by one of the authors and submitted to 
several dairymen for examination. It could not by any 
physical test be distinguished from creamery butter. (This 
butter did not include drippings from the milled curd.) 

In order to make whey butter a profitable product, the 
cheese factory should have at least 10,000 pounds of milk 



214 DAIRY TECHNOLOGY 

daily. A separator is necessary in order to secure the cream 
in good condition. The whey should be run through the 
separator while hot, as soon as possible after being drawn 
from the curd. A cream of not less than thirty per cent 
fat should be secured, pasteurized and cooled, ripened with 
a starter, and treated in every way the same as cream in a 
whole-milk creamery. 

The butter can be made more economically by gathering 
the cream from several cheese factories and taking it to 
one central point for proper ripening and churning. But it 
is essential that each factory take proper care of the cream 
and deliver it in a sweet, clean condition. 

The skimming of whey is practiced commonly in fac- 
tories making cheddar or American cheese, as well as in 
Swiss-cheese factories. Some authorities claim that ched- 
dar cheese when made under most favorable conditions 
leaves so little fat in the whey that the cost of recovering 
it would hardly be met by the value of the fat secured. 
When the cheese maker is deriving direct profit from the 
whey cream, he may so handle the curd while in the whey 
that a very considerable portion of the fat that should go 
into the cheese is left in the whey to be recovered by the 
separator. 

Disposal of Whey Butter. — It is very evident that whey 
butter must be so branded as to distinguish it from creamery 
butter. So much whey butter is of poor quality that this 
product, no matter how good it is, brings a lower price 
on the market than does creamery butter. To some ex- 
tent the local patrons of the cheese factory may, however, 
use the whey butter. This latter is of the same value to 
them as a similar grade of creamery butter. However, 
if whey butter of high quality be offered on the market 
for some time, it will soon gain a favorable reputation 



WHEY BUTTER 215 

and be able to compete with butter made from natural 
cream. 

Profits from Whey-butter Making. — Each succeed- 
ing year shows an increase in the volume of whey butter 
manufactured. Last year (1910) Lafayette County, Wis- 
consin, alone, produced 84,000 pounds of this product. 
The various separator companies have constructed sepa- 
rators especially adapted to the separation of whey. 

A cheese factory receiving, on an average, 6000 pounds 
of milk per day would handle 2,190,000 pounds of milk per 
year. On a basis of 3 pounds of whey butter from each 
thousand pounds of milk made into cheese, 6570 pounds 
of butter would be made in one year. If this butter is 
properly made it should sell for an average price of 25 cents 
per pound. The income from this butter would be 
$1642.25. 

In many places one half the gross income from whey 
butter is divided among the patrons. This would leave 
$821,125 as the cheese factory's share. From this must 
be deducted about $500, which includes the interest on 
the extra investment, depreciation in value and the charge 
for labor and fuel. The net profit to the cheese factory 
would amount to about $321.25 for the year. 



CHAPTER XXVI. 

MILK SUGAR. 

Milk sugar or lactose (C12H22O11 + H2O) is probably 
found in the milk of most mammals, and, so far as known, 
is found nowhere else in nature. Richmond has shown 
that the milk of the goat, the ass and the Egyptian 
gamoose or water-buffalo contain lactose. Richmond and 
Pappel also found that the sugar in the milk of the 
gamoose in winter differed from lactose. This sugar they 
called "Tawfikose." Sugar of mares' milk has the prop- 
erty of easily undergoing alcohoHc fermentation, a property 
not possessed by lactose from cows' milk. According to 
Richmond and Pappel, sugar of human milk is not identical 
with that of cows' milk. The milk sugar of commerce 
is derived from cows' milk of which it forms about five 
per cent. It is but slightly sweet, hardly a hundredth as 
sweet as cane sugar. 

This product is used in modifying milk for feeding in- 
fants and invalids, as a diluent in various strong drugs, 
in the preparation of medicinal powders, and in the manu- 
facture of pentanitro-lactose, which forms a part of some 
high explosives. 

History and Development of Milk-sugar Manufac- 
turing. — Milk sugar is said to have been discovered by 
accident early in the eighteenth century by a peasant 
in Switzerland who was making cheese. The cheese 
having been hung up in a bag to drain for some time, 
this observing Swiss noticed a few crystals that had been 

216 



MILK SUGAR 217 

formed by the evaporation of the whey. A druggist, 
to whom these crystals were shown, predicted that, if 
the product could be manufactured in quantities, it would 
become an important article of commerce. In the first 
half of the nineteenth century, milk sugar was being manu- 
factured by very crude methods in Switzerland, Holland 
and Germany. The sugaring processes occupied about 
fourteen days and the product then contained many im- 
purities. But there was great demand for even this 
impure product and the industry grew. Switzerland con- 
trolled the milk sugar industry, and supplied the markets 
of the world. In time the United States became the chief 
customer of Switzerland, taking about three-fourths of the 
$60,000 worth annually exported from that country.^ 

The first attempt to manufacture milk sugar in this 
country was made in 1881 by Dr. Gerber. He worked 
for about two years in Little Falls, N. Y., and then gave 
it up, declaring that, on account of the poor quality of 
milk produced in the United States, Switzerland need 
never fear competition in the milk-sugar industry from 
that source. 

However, by 1890 the milk-sugar industry was fairly 
well established in this country and was developing 
rapidly. American improvements in the process of pro- 
duction have made possible a product of much higher 
purity than the sugar formerly imported from Switzerland. 
To-day milk sugar is exported from this country to Europe 
and has to a considerable extent replaced the Swiss product. 

Milk-sugar Making in the United States. — Alvord, in 

1897, reported four or five milk sugar factories in Illinois, 

New York and Ohio, using whey from neighboring cheese 

factories, for which they paid from 4 to 7 cents per hun- 

^ Alvord in United States Dept, of Agriculture Yearbook, 1897. 



2l8 DAIRY TECHNOLOGY 

dred pounds. The largest factory of thjs kind in the 
world is located in Illinois and has a capacity of one and 
a half tons of milk sugar per day. They get on an average 
3.4 pounds of sugar from 100 pounds of whey. At this 
factory the whey from casein making as well as the whey 
from cheese factories is used, thje sugar from the former 
source being of just as high quality as that from the latter. 

The Process of Manufacture. — Whey, acidified to 
about one per cent of hydrochloric acid, is heated in large 
vats to the boiling-point with steam. This precipitates 
the albumen. The solution is then made neutral with 
calcium hydroxide, evaporated in a vacuum pan to a 
syrupy consistency (22° to 25° Baume), and filtered 
through a series of cloths in a high-pressure filter press. 
When sufficient syrup has accumulated, it is again run 
into the vacuum pan and evaporated, at about 110° F., 
to a much richer syrup. This latter is drawn out into 
shallow boxes, where it cools and crystallizes, in 24 to 48 
hours, into what appears to be a yellow sand. This is 
crude sugar, and must be passed through several proc- 
esses of purification. 

This mass is first washed with cold water in a centrifuge. 
The centrifuge is a combination of drums with perforated 
walls and fine sieves. The syrup is thrown out through 
the sieves and the sugar crystals are retained within 
them. The crystals are here washed with cold water 
to remove calcium chloride and other soluble impurities. 
The washings and the syrup thrown out by the centri- 
fuge are saved and the contained sugar recovered. The 
sugar crystals are redissolved in hot water, certain chem- 
icals are added and the solution is allowed to stand over 
night. In the morning the clear liquid is siphoned off. 
The settlings in the bottom of the tank are filtered and 



MILK SUGAR 219 

the filtrate is added to the solution previously siphoned 
off. 

This is then heated to about 170° F., and filtered through 
bone black to remove coloring matter and other impuri- 
ties. This filtered solution is now condensed to the 
proper point in a vacuum pan. The resulting pasty mass 
is passed through the centrifuge and washed, and put 
upon tray frames with cloth stretched over them to dry. 
These trays are placed upon racks in a drying room and 
the sugar dried at 60° C. (140° F.). When dry it is pow- 
dered in a ball mill and bolted in a manner similar to that 
of bolting flour in a flour mill. The product is a fine 
white powder, and is put into barrels holding about two 
hundred pounds for shipment. 

By-Products of Milk-sugar Making. — The raw mate- 
rial used in the manufacture of milk sugar is a by-product 
of another industry, yet the sugar industry itself pro- 
duces a by-product. This is the proteid matter, mainly 
albumen, that is taken from the filter press. This proteid 
matter is placed on cloth racks, kiln dried, and sold as food 
for poultry and stock. 

Alvord reports the use of milk-sugar-factory by-prod- 
ucts for pig feeding. Young pigs just weaned were 
bought and fed on nothing but waste from the sugar fac- 
tory. They thrived and fattened so that they were ready 
to kill at six to seven months of age. This feed is highly 
nitrogenous, and evidently a very narrow ration. It 
seems probable that even better results would be secured 
by using a highly carbonaceous food in combination with 
the sugar-factory waste. 

Mysost. — Instead of using the whey from cheese fac- 
tories for the manufacture of milk sugar, it may be con- 
verted into a kind of cheese known as Mysost. Although 



220 DAIRY TECHNOLOGY 

made in this country to some extent, this cheese is more 
especially a product of cheeseries in Norway, Sweden and 
Denmark. It has a yellowish-brown color, the consistency 
of firm butter, and a sweet, characteristic flavor similar to 
a concentrated evaporated milk flavor. In this country 
it is marketed in paraflined pound cubes, or in cylindrical 
shapes, wrapped in tinfoil. 
The method of manufacture is as follows:^ 

" As soon as the curd of the regular cheese is removed 
from the whey, the whey is strained and is put in a kettle 
or large pan over the fire and the albuminous material 
which rises to the surface is skimmed off. The whey 
is evaporated as rapidly as possible with constant and 
thorough stirring. When it has reached about one- 
fourth its original volume the albumin previously skimmed 
off is returned and stirred thoroughly to break up all possi- 
ble lumps. When the whey has attained the consistency 
of thickened milk it is poured quickly into a wooden trough 
and stirred with a paddle until cool to prevent the forma- 
tion of sugar crystals. This can then be molded into the 
desired form." 

Its composition, according to Dahl, is: Water, 23.57 
per cent; Fat, 16.26 per cent; Proteids, 8.88 per cent; 
Milk sugar. Lactic acid, etc., 44.84 per cent; Ash, 4.76 

per cent. 

^ Bu. An. Ind., Bid. 105. 



CHAPTER XXVII. 

CASEIN. 

The separation of casein from milk for cheese-making 
purposes has been practiced for over two thousand years, 
but only during the last few decades has scientific research 
revealed the multitude of uses to which this product may 
be put in the technical industries. Casein to-day is manu- 
factured on a large scale and used in the preparation of 
paint, glue, paper, dress goods, as imitation ivory, horn, 
etc., and as a concentrated foodstuff. 

Casein exists in milk not in true solution, but in sus- 
pension. It may be separated out by the following means : 
(i) filtration through a porous clay filter, (2) centrifugaliz- 
ing) (3) precipitation by dilute acids, (4) precipitation by 
ferments, and (5) precipitation by salts. Casein, when 
dried, forms a horny mass insoluble in water or dilute acids, 
but soluble in alkalis and concentrated acids. 

Statistics show that the use of dry casein has increased 
100 per cent during the last five years, and that Germany 
consumes about four thousand tons annually. The entire 
consumption in Europe and America is placed at about 
fifteen thousand tons. The United States Census of 1909 
places the casein production in this country at almost 
seven thousand tons, an increase of 12 per cent in five 
years. 

Preparation of Casein. — In the chemical laboratory, 
casein is prepared by diluting the milk to about five times 
its volume, and adding sufficient acetic acid to make the 



22 2 DAIRY TECHNOLOGY 

acidity of the solution one tenth per cent. This causes 
the precipitation of the casein. It is then filtered and 
washed well with distilled water. This latter will dissolve 
out the acid and sugar in the residue. This residue on 
the filter is dried and redissolved in the least possible 
amount of ammonia, and upon standing awhile, the fat 
will rise to the top. The liquid can then be siphoned off 
and filtered. The filtrate is again precipitated by acetic 
acid. This precipitate is redissolved in ammonia and the 
process is repeated three or four times until it is pure and 
white. This casein is now rubbed in a mortar with 80 per 
cent alcohol and the alcohol poured off. This treatment 
with alcohol is repeated several times, absolute alcohol 
being used the last time. This is followed by treatment 
with ether until all the alcohol is removed. The product is 
pure casein which, when thoroughly dried, is in a powdery 
condition. However, the preparation of casein for com- 
mercial purposes is quite a dift'erent process. 

Commercial casein is prepared from skim milk on quite 
a large scale, usually in a room or building adjoining a 
large whole-milk creamery. 

Five thousand or more pounds of skim milk are placed 
in a jacketed vat and heated to about 130° F. Then 
sufficient acid is added to precipitate the casein. In some 
cases commercial sulphuric acid is used in the proportion 
of one pint of acid diluted in water to one thousand pounds 
of milk. At other factories the kind and quantity of acid 
used are considered trade secrets. The curdling should 
take place under proper conditions. If an excess of sul- 
phuric acid or too strong acid is used, the curd will be 
discolored. 

When the milk has been coagulated, the whey separates 
and is drawn oft". To faciUtate and hasten this process, 



CASEIN 223 

the curd is broken into small chunks and piled on a drain- 
ing tabic or rack covered with coarse cloth. Here the 
whey and acid are washed out by streams of cold water. 
The curd is then allowed to drain for two or more hours 
until it becomes dry enough to be ground. Or it may be 
placed in a press similar to an upright cheese press and 
left there over night. The next morning the curd is passed 
through a curd mill, such as is used in the manufacture 
of cheddar cheese, and ground into small pieces. 

The curd is then placed upon drying trays, which con- 
sist of coarse cloth stretched over a wooden frame. These 
trays of curd are placed in the drier and left there until 
the pieces of curd are quite dry and horny. The drier 
may be either of the horizontal or vertical type. In both 
cases it consists of a heated space in which the trays are 
placed in tiers. At one end, or at the bottom of the drier, 
is a power-driven fan that forces a current of air over a 
hot radiator and thence to the trays of curd. A tempera- 
ture of about 120° F. is maintained for about twenty- 
four hours. 

— ' At the end of this time the curd is dry and is taken 
from the trays, put into sacks holding about one hundred 
pounds each, and shipped. At this stage the curd is in 
small, yellowish white, irregular lumps. If the curd is 
not thoroughly washed before drying, the presence of milk 
sugar and heat will cause a discoloration and a flinty 
appearance of the curd. This greatly lessens its solu- 
bility and commercial value. 

One hundred pounds of skim milk will yield about 3I 
pounds dried casein, which contains about twelve per 
cent of moisture. For this dr)- curd the casein companies 
pay about seven cents per pound, which is equivalent to 
24.5 cents per 100 pounds of skim milk. 



224 DAIRY TECHNOLOGY 

According to the Union Casein Company the following 
equipment is needed for the manufacture of casein from 
skim milk: 

" The machinery is not expensive; it consists of a skim- 
milk vat, unlined; a press, one curd mill and wooden drying 
closet. The kiln covers a space of about four feet high, 
twenty-two feet long and six feet wide, built along the wall of 
(preferably) the second floor. This size is suitable for drying 
curd or casein from 24,000 pounds of skim milk. (A larger 
or smaller size can be made proportionately.) The radiator 
and ball-bearing fan are the principal parts required for the 
making of the drier. Radiator costs $48.00; fan $35.00. In 
addition to the dryer you will require 12 trucks, each of 
which holds 30 wire trays. One truck and one set of trays are 
required for drying the wet curd extracted from 2000 pounds 
of skim milk. The trucks cost $2.50 each and the trays $9.00 
per dozen. The curd flaking machine costs $55.00; press 
$35.00. One press is required for each 12,000 pounds of 
milk." 

This commercial casein must be purified if intended for 
certain technical uses. To accomplish this the casein is 
macerated, and dissolved in dilute alkali at a high temper- 
ature, cooled, reprecipitated with an acid, drained and 
washed repeatedly with water, and finally pressed and dried. 

Casein from Buttermilk. — The large central creamery 
plants of to-day are taking up side lines, and manufacturing 
several by-products. One of these is casein from butter- 
milk. 

The process of recovering casein from buttermilk is 
similar to that of recovering casein from skim milk. But 
the physical and chemical condition of the buttermilk casein 
necessitates certain modifications. At different factories 
slightly different methods are used, but in a general way the 
processes are the same. 



CASEIN 225 

The buttermilk, when drawn from the churn, Is pumped 
into large vats or tanks, steam is turned directly into the 
buttermilk, and the temperature is brought to about 160° F. 
The hot buttermilk is left undisturbed for several hours, 
or over night. It is then run over a cooler into a smaller 
vat, for convenience in handling, and the temperature 
brought to about 100° F. Sulphuric acid is added in the 
proportion of about six quarts of acid to 300 gallons of 
buttermilk. The proportion is varied with the season of 
the year, the acidity and the condition of the buttermilk. 
An excess of acid will produce a dark-colored casein that 
has a low market value. Insufficient acid causes incom- 
plete gathering of the curd; hence, many small particles 
are lost in the whey. Within one hour from the time the 
acid is added the whey may be readily drawn off and the 
curd put to press. The pressing, grinding and drying of 
the curd is carried on in a manner similar to that of han- 
dling curd from skim milk. 

Casein from buttermilk differs from casein from skim 
milk in the following particulars: 

Buttermilk casein is darker in color, contains a higher 
percentage of fat, is less soluble, and cannot be used so 
extensively nor for such high-grade products as can skim- 
milk casein. The former has a market value from ten to 
sixty per cent lower than that of the best-grade skim milk 
casein. 

Casein Glue. — The crude casein may be converted into 
a glue by the following simple process: To the casein add 
one-fourth of its weight of distilled water and one to four 
per cent of bicarbonate of soda. Mix thoroughly, then add 
a quantity of distilled water equal to the original amount 
used, to complete the solution, and let it stand from five 
to six hours. At the end of this time the glue will be 



226 DAIRY TECHNOLOGY 

ready for use. An antiseptic should be added to prevent 
fermentation. 

There are many patented formulas for the manufac- 
ture of casein ghie. Borax, ammonia, lime, and various 
alkaline salts are used in this connection singly or in com- 
bination. 

Closely allied to the casein glues and of similar composi- 
tion are several kinds of casein i)utties and stopping. 
These materials are employed in wood working and cabinet 
making. 

Casein Paints. - It has long been recognized that the 
addition of milk to whitewash increases its adhesiveness 
and durability. This result is principally due to a combina- 
tion of the casein and lime. This compound, formed by the 
combination o{ casein with certain other substances, forms 
the basis of all the numerous casein paints of to-day. 

Scherer gives the following formula for a paint for out- 
side work: 

loo parts by wcii^hl of casein, soluble in alkali. 
loo " " " " caustic lime from marble. 
800 " •' " '• knigated chalk. 
2 to 2\ " " " " ultramarine (for white only). 
I part " " " borax. 

On the market to-day are casein paints of all kinds 
and colors, liquid and powder, some of which are: Casein 
Enamel Paint, Kalsomine Wash, Quick-Drying Casein 
Paint, Cold Water Paint, Boiled Oil Substitute, Water- 
proof Paint for Playing Cards, Casein Cement Paint, etc. 
Similar paints are prepared by the use of the whole milk 
instead of merely the casein constituent. 

Milk-cement Paint. — A most effective and durable 
paint can be made from milk and cement by mixing one 
gallon of milk and about four pounds of Portland cement, 



CASEIN 227 

adding sufficient Venetian-red j)aint powder (cost, 3 cents 
per pound) to give a g(xxJ c(jl<jr. Any other paint powder 
of a different color can be used as well. This should be 
stirred thoroughly. The onl> objection to this is that the 
milk will not hold the cement in suspension on account of 
the great weight of the cement. It has to be thonjughly 
stirred all the time during its use. 

About six hours after applying, the coat of paint will be 
dry, and it is not affected by water. The authors have 
used this paint with satisfaction. It seems to petrify the 
surface of the wood, which is evidently the reason why it 
is so preservative in its effect. 

If water is used instead of milk, the paint will not adhere 
so well to the wood. 

The paint when mixed with a little extra cement is a 
good substance for painting trees which have been injured. 
When painted on the bottom of the trunk of trees, it pro- 
tects against rabbits gnawing them. 

Plastic Masses from Casein.' — " Like all substances 
possessing strong adhesive properties, casein is specially 
adapted for the preparation of plastic masses, which can 
be molded, either in a mixture with organic substances 
like sawdust, wood meal, paper, etc., or alone in the form 
of paste or a more or less dry powder, and set hard when 
dry. Casein mixed with lime or other alkaline material 
can be converted, by the addition of a little water, into a 
plastic mass which, though very gradually, dries in the air 
to a transparent mass as hard as bone, and can be stained 
any color. In this condition it can be turned in the lathe 
or worked with any other cutting tool. When plastic casein 
is mixed with other substances, such as organic or fmely 
powdered inorganic materials, the resulting masses are 
endowed with the property of drying quickly, especially 
under the influence of warmth. Care must, however, be 

'Robt. Schercr. — Casein, Its Preparation and Utilization. 



228 DAIRY TECHNOLOGY 

taken in the drying process, owing to the fact that all 
masses containing much water shrink and easily crack 
while drying. 

"The adhesive properties of casein have already met with 
extensive industrial application. Great success has at- 
tended, for example, the attempts made to render celluloid 
uninflammable by admixtures of casein; and special men- 
tion will be made later of the newest celluloid substitute, 
galalith. This affords an instance of how modern ingenuity 
has enabled a raw material, hitherto of but slight use 
technically, to become of great industrial utiHty." 

And so we have an imitation ivory and horn, and insu- 
lating preparation, and antiradiative and anticorrosive 
substance for covering steam and refrigeration pipes, a 
covering for floors that resembles linoleum, imitation 
leather, etc. 

Consul General O, G. D, Huges of Coburg, Germany, 
reports the following: 

''At the Hygienic Milk Supply Exhibition which was 
lately held at Hamburg, the Vereinigten Gummiwaren- 
Fabriken, of Hamburg and Vienna, exhibited a number of 
objects which seemingly had nothing to do with the Hy- 
gienic Milk Supply. There were shown nicely arranged in 
glass boxes, combs, seemingly made of bone, cigar holders 
with amber-colored mouthpieces, knives and forks with 
handles similar in appearance to ebony, ferrules for um- 
brellas and canes, and bells, rings, chess figures, dominoes, 
etc., also a small table with an inlaid marble slab, and finally 
a number of thick slabs and staves of every imaginable 
variation of marble colors, but of considerably less weight 
than marble. These objects were made of galalith, or milk 
stone." 

Manufacture of Galalith. — This peculiar substance 
known as milk stone is prepared, according to Scherer, by 
the following method: Casein, prepared by precipitation 
with rennet instead of an acid, is mixed with 13 times its 



CASEIN I 229 

weight of water. This contains in solution 2^ parts of 
caustic soda per 100 parts of dry casein. This produces 
a milky Hquid, which may be cleared by adding a larger 
quantity of 5-per-cent caustic soda. The clear solution 
is treated with an acid to precipitate the casein, is dried 
and then moistened with a little acid to restore its plas- 
ticity. To prepare a hard casein mass (milk stone), the 
casein is treated with formaldehyde, pressed or molded 
into any desired form. Any desired coloring matter may 
be added to the casein before its treatment with formalde- 
hyde, to produce imitation ebony, marble, etc. The final dry- 
ing must proceed very slowly in order to prevent cracking. 

Galalith, in a general way, resembles celluloid. The 
specific gravities of the two substances are about the same, 
Galahth is harder and less elastic than celluloid; it is hard 
to cut, and inchned to chip; it takes a higher polish than 
the celluloid; it cannot be made into so thin transparent 
sheets, and it absorbs some water when soaked. 

Casein in the Textile Industry. — Casein is used largely 
in calico printing, and more rarely in the finishing. Finish 
refers to a glossy dressing like starch. The gummy am- 
moniacal solution of casein is employed as a medium for 
printing and fixing powdered pigments that will stand 
alkali. Fairly well fixed colors are obtained, when the 
ammonia has been driven off by vigorous drying and steam- 
ing. Casein dissolved in lime water may be used for the 
same purpose as the ammoniacal solution. In this case 
the colors are fixed by the action of the carbonic acid in 
the air, the products being calcium carbonate and insoluble 
casein. 

Following are some of the casein products used in this 
industry: caseo gum, to assist fibers in absorbing dyestuffs; 
glutin, a glaze for dressing certain fabrics; and a product 



230 DAIRY TECHNOLOGY 

for waterproofing cloth and for loading silk (making it 
appear heavier than it really is). 

Casein Foodstuffs. — The importance of proteids in 
the food of man is generally recognized. This essential is 
usually furnished to a large extent in the form of meat, 
but the proteids of milk may form a very satisfactory 
substitute for meat, and there are on the market for this 
purpose a number of casein products. Lactarine, Sanato- 
gen and Galactogen are made up mostly of casein. Eulac- 
tol is an evaporated milk similar to our common milk 
powder. Plasmon, Nutrium, etc., are products consisting 
of casein, milk sugar, and salts. 

Casein in the Paper Industry. — " An important part 
is played by the adhesives in the industries wherein paper 
is employed, both in order to inseparably fasten together 
individual sheets of paper, convert paper pulp into a mould- 
able condition, and also for the application of thin layers 
of colouring matter or other coatings may be either mat or 
more or less glossy, but in any event must be able to with- 
stand to a certain extent the influence of moisture. For all 
these purposes casein is admirably adapted, since it will 
stick sheets or bands of paper together and forms thin 
coatings of considerable elasticity both alone or in associa- 
tion with other substances, colouring matters in particular. 
When a solution of casein is treated with small quantities 
of formaldehyde, and the article coated with the prepara- 
tion exposed to the air, a number of new products can be 
obtained. Thus, for instance (by patented processes), we 
obtain waterproof cardboard boxes and cartridge cases, 
washable wall papers, washable paper garments, coloured 
papers, art papers, transfer papers and so on. Utensils, 
more particularly basins, dishes and the like, made of paper 
pulp or millboard, can be rendered waterproof by treat- 
ment with formaldehyde, and used for a variety of purposes, 
e.g., as developing dishes in photography. Similarly, card- 
board treated in the same way can be used for stereo- 



CASEIN 231 

type matrices, and will keep for any length of time, by 
reason of its lightness and durabihty. It is thus evident 
that the field of application open to casein is practically 
illimitable." 1 

Other Uses for Casein. — Photographic plates may be 
made of casein and have some advantages over glass and 
celluloid, being lighter in weight and less fragile than glass, 
non-inflammable, and less likely to curl during developing 
than celluloid. 

Casein even forms an important part in a brand of shoe 
poHsh. It is used to treat pulp board roofing and makes 
a fireproof covering that is not softened by the heat of the 
sun. Wooden casks used for beer, wine, etc., may be coated 
inside with a solution of casein and formaldehyde. This 
makes an impervious seal. Artists and scene painters 
require that their canvas be primed before it is painted. 
For this purpose casein gives better results than chalk, 
driers, etc., because it does not crack with age. The soap- 
making industry claims its share of casein for use in toilet 
soaps, perhaps because the casein aids in holding and re- 
enforcing the perfumes. 

Buttermilk Poultry Food. — A poultry food, concentrated 
and high in protein, is made as follows: 

Buttermilk is heated in tanks to about 160° F., and al- 
lowed to stand until the curd has settled. The whey is 
then drawn off, and the SQ^iment, a mass of curd with a 
thick, creamy consistency, is run into barrels and sold as 
poultry food. This product, though heated to a high 
temperature, is not sterile, but, because of its thick con- 
sistency, has good keeping qualities. Like sweetened con- 
densed milk, it contains insufficient moisture for bacterial 
growth. 

1 Robt. iSchercr — Casein, lis Preparation and Utilization. 



CHAPTER XXVIII. 

FERMENTED MILKS. 

During the past few years there has been a great in- 
crease in the consumption of buttermilk and other fer- 
mented milks. Buttermilk tablets and numerous other milk 
preparations have appeared on the market, for most of 
which a certain medicinal as well as food value is claimed. 
These are sold under various names, such as Zoulak, 
Vitallac, Yoghurt, Matzoon, Bacillae, Kefir, Kumiss, 
Lacto-Bacilline, etc. 

In practically all these fermented milks, lactic-acid fermen- 
tation is the main one. This may or may not be accompa- 
nied by a fermentation causing alcohol and carbon dioxide to 
be formed. This latter is brought about chiefly by yeast 
ferments acting on the milk sugar and other added sugars. 

Food Value. — Since these products are all made of 
milk, either whole or skimmed, the composition of which 
is but slightly changed by the fermentation it undergoes, 
it is evident that the food value of these fermented products 
is practically the same as that of fresh milk. There is 
possibly an increased digestibiHty of the casein, due to 
the fact that it has been precipitated and is in a very 
finely divided condition. Those products containing alco- 
hol and carbon dioxide are said to have a stimulating action 
upon the digestive organs. 

Principles Involved. — ^ In Metchnikofi"s book "The 
Prolongation of Life " there is a chapter on " Lactic 
acid inhibiting intestinal putrefactions." He states that 
the use of fermented milks in combating autointoxi- 

232 



FERMENTED MILKS 233 

cation — toxic fermentations in the intestines — is based 
on the principle that the presence of lactic acid bacteria, 
and the products of their growth, prevent or inhibit the 
growth of the toxin-producing germs in the intestinal 
tract. It is probable that the beneficial results secured 
by the use of fermented milks are due to a combination 
of causes: First, the subduing influence of the lactic-acid- 
producing germs on undesirable ferments; second, the 
inhibiting effect of the lactic acid on toxin-producing 
germs; third, the influence of substances not necessarily 
acid in nature, secreted or produced by the milk ferments; 
and fourth, the stimulating effects and nutritive value of 
all the milk components. 

Whatever the physiological action may be, it is certain 
that there are certain benefits to be derived from the use 
of fermented milks. 

Tablet and Capsule Cultures. — Rogers^ reports that 
some brands of tablets and capsules, sold under various 
trade names, purporting to contain great numbers of the 
Metchnikoff bacillus or Bacillus bulgaricus, were examined 
in the Dairy Division laboratory, and were found to con- 
tain very few of these desirable bacteria. When these 
tablets were introduced into sterile rnilk, the resulting 
fermentation was not of the desirable type. The milk 
was curdled, but the curd showed evidence of the pres- 
ence of peptonizers and gas producers. One tablet which 
was advertised to contain " 5,000,000 active Metchnikoff 
units " was found to contain about a million bacteria, 
nearly all of which were of the class usually considered un- 
desirable inhabitants of the digestive tract. The findings 
of this and other laboratories indicate that little reliance 
can be placed on dried cultures of B. bulgaricus. 
1 U. S. Dept. of Agri., Bii. An. Ind., adih An. Kept. 



234 DAIRY TECHNOLOGY 

However, this does not apply to dry cultures of B. acidi 
lactici, because these are in daily use in butter and cheese 
factories throughout the country, and are known to contain 
a sufficient number of virile lactic bacteria to insure a 
desirable fermentation. So-called buttermilk tablets are 
simply dry cultures pressed into tablet form. 

The germ Bacillus bulgaricus is capable of producing 
about two per cent of lactic acid in the milk, while the 
ordinary lactic-acid-producing bacteria in milk produce 
only a maximum of about one per cent acid. 

Buttermilk. — Most common of all fermented milks is 
the by-product of the butter-making industry. Butter- 
milk is the milky portion of the cream that remains after 
the fat has been churned out of the cream. As cream is 
normally churned sour, the casein of the buttermilk is 
in a precipitated and very finely divided condition. The 
casein remains suspended in the liquid for several hours, 
but gradually settles to the bottom, leaving a transparent 
whey on top; occasional stirring keeps the buttermilk 
in its homogeneous milky condition. This universally 
common beverage needs no further description. When 
it comes from fresh and properly ripened cream it is a 
most refreshing and delicious drink. 

Composition. — The composition of buttermilk does 
not differ essentially from that of skim milk. Its fat 
content is the one variable factor, and this depends upon 
the completeness with which the fat was churned out. 
The following is a fair example of the composition of aver- 
age buttermilk : p^^^^„, 

Water 90 ■ 3Q 

Fat 0.50 

Casein and albumen 3 • 60 

Milk sugar 4 . 06 

Lactic acid o . 80 

Ash 0.75 



FERMENTED MILKS 



235 



Artificial Buttermilk. — Natural buttermilk from fresh 
cream ripened with a lactic culture is perhaps the best 
quality of this product that can be secured; but in many 
places this cannot be obtained at any price. IMuch of the 
buttermilk of to-day has undesirable flavors in it. Because 




Fig. 46. — Progress milk fermenting maciiinc. 



of this fact, preparations are now found on the market 
which have all the characteristics of good buttermilk, but 
are not by-products of butter making. These preparations 
are made of whole milk, of partly skimmed milk, or of 
wholly skimmed milk. A method of making a so-called 
"skim-milk buttermilk " is as follows: 



236 DAIRY TECHNOLOGY 

Milk to be used may be, i, skim milk fresh from the sep- 
arator; 2, pasteurized skim milk; or, 3, skim milk to which 
5 per cent of whole milk has been added, to make the fat 
content similar to that of natural buttermilk. A large quan- 
tity of a good starter or pure culture of lactic-acid bacteria 
is next added, and the temperature brought to 70° F. 
Enough culture is added to have the milk curdled at a time 
when it will be convenient to churn it. The development of 
too much acidity or the ripening at too high a temperature 
causes the skim milk to " whey off " after it has curdled. 

When thoroughly curdled the skim milk is placed in 
a churn and churned for forty minutes, just as cream is 
churned in making butter. The churning process thor- 
oughly bleaks up the curd particles and produces a smooth, 
thick liquid, which cannot be distinguished from ordinary 
good buttermilk. 

Immediately after the buttermilk leaves the churn, it 
should be cooled to 50° F., or less, to prevent further de- 
velopment of acidity. Ordinary milk and cream coolers 
with enlarged holes in the distributing receptacle may be 
used satisfactorily for cooling buttermilk. 

It is well to strain the buttermilk through one thickness 
of cheesecloth to remove any pieces of curd that may not 
have been broken up. The buttermilk is then put into 
bottles or cans and held at a low temperature until deUvered. 

Bacillus Bulgaricus for Buttermilk. — One objectionable 
property possessed by both natural and artificial butter- 
milk is that the precipitated casein settles out in a few 
hours, leaving clear whey on top. The casein is easily 
mixed with the whey again, but the settHng of the casein 
may be prevented by using the Bacillus bulgaricus as the 
active ferment. This produces a viscous curd, that will 
not settle out. 



FERMENTED MILKS 237 

If, in making artificial buttermilk, the skim milk be in- 
oculated with cultures of both the common lactic-acid 
producer and the Bulgarian type, good results will not be 
obtained, because the two types of organisms have different 
optimum temperatures for growth. The common lactic- 
acid producer gives best results at about 70° F., while the 
Bulgarian type should be grown at about 100° F. 

To get the best results, then, a batch of pasteurized 
skim milk is inoculated with a lactic-acid culture, and the 
milk ripened exactly as is done when making a starter in 
a creamery. An equal quantity of pasteurized skim milk 
is inoculated with the Bulgarian t>pe of starter and incu- 
bated at about blood heat from twenty-four to thirty hours. 
It will then contain about two per cent acid (as much as 
3 per cent acid will develop in 3 days) . These two batches 
of sour milk are then mixed by pouring them both into a 
churn and churning the milk until the curd is all broken up 
and a smooth product is secured. 

Buttermilk Tablets. — There are several brands of butter- 
milk tablets sold under various trade names. These are 
useful in making imitation buttermilk on a small scale in 
the home. One method of using these tablets is described 
by the manufacturers as follows: 

" Take a quart of fresh, rich milk, put it in a clean jar 
or other vessel of glass or earthenware, and add thereto 
one-third of a quart of hot water. The amount of water 
may be varied according to the richness of the milk, the 
taste of the individual who is to be served, or the require- 
ments of the patient if it is to be used in the sick-chamber. 
The purpose in adding hot water is to raise the temperature 
of the milk to body heat. A pinch of salt is now stirred 
into the mixture together with one " Lactone " tablet 
which has been previously powdered, the whole being well 
mixed until the tablet is dissolved. The jar is then covered 



238 DAIRY TECHNOLOGY 

and set aside where it will be subjected to an even tempera- 
ture, such as that of the average kitchen. In twenty-four 
to forty-eight hours, depending upon the temperature, the 
buttermilk will be ready for use. One can easily tell, by 
the appearance and flavor of the milk, when the process 
of thickening and fermentation has proceeded far enough. 
The buttermilk should then be set away in the ice-box 
or cellar. Before using, it should be thoroughly stirred 
with a spoon or egg-beater until perfectly smooth." 

This artificial buttermilk is sometimes modified at soda 
fountains by the addition of vIchy or seltzer, by beating an 
egg into it, or by adding vanilla, lemon or other flavors. 

Kefir. — Fermented milks have been used by the people 
of southern Russia, Turkey and the Balkan countries, for 
many centuries. There are no records and but few tradi- 
tions of the origin of the fermented milks they use, and it is 
probable that their preparation and use developed gradually 
by cumulative experience. 

One of the first fermented drinks known to Europeans 
was kefir. This was first made in the Caucasus Moun- 
tains from milk of cows, sheep and goats. Different 
tribes made this drink under different names ^ such as 
" Hippe," " Kepi," " Khapon," " Kephir " and " Kapher," 
all of which names are said to be derived from a root sig- 
nifying a pleasant taste. 

The fermented milk forms a large part of the food of the 
Caucasian mountaineers. The milk is prepared in leather 
bottles made of goat skins. These bottles are hung where 
the atmosphere is supposed to have the temperature 
favorable to the proper fermentation of the milk. This 
may be in or out of doors, in the sun or in the shade. A 
favorite place for hanging the bags is near a doorway where 
they may be shaken by each passer-by. 

1 U. S. Dept. of Agr., Bii. An. Ind., An. Rcpt., 1909, 



FERMENTED MILKS 239 

In order to prevent the escape of gas when drawing milk 
from the bag, a string is first tied around the neck so 
that the quantity wanted is between the stricture and the 
mouth of the bottle. 

One characteristic of kefir that especially distinguishes 
it from other fermented drinks is the so-called kefir grain, 
which is used to start the proper fermentation. These 
kefir grains are small, yellowish, convoluted masses, con- 
sisting largely of bacterial threads and yeast cells, held to- 
gether by more or less dried milk. When these grains are 
added to milk they induce a fermentation of the lactose, 
forming alcohol and carbon dioxide. 

Freudenreich^ describes four organisms that he isolated 
from kefir grains. Of these, one was yeast to which he 
gave the name " Saccharomyces kefir"; this organism 
was found to grow best at 22° C. (72° F.); but not at all 
at 35° C. (95° F.). This yeast ferments maltose and cane 
sugar, but not lactose. It produces a peculiar flavor in 
milk. The same investigator found two organisms of the 
lactic-acid type, but they formed gas in lactose media. 
Another organism described is a long, slender bacillus to 
which Freudcnreich gave the name " Bacillus caucasica." 
The properties of this organism indicate that it resembles 
very closely the well-known Bacillus bulgaricus. If Freu- 
denreich's description is accurate, B. caucasicus differs from 
B. bulgaricus in forming gas from lactose and in being feebly 
motile. No one of these organisms grown alone produced 
kefir, but when the four together were grown in milk, 
typical kefir was produced on the first or second transfer. 

Various investigators have found different organisms 
in the kefir grain. It seems probable that kefir may be 
produced by any combination of bacteria and yeasts that 
1 U. S. Dept. Agr., Bu. An. Iiid., An. Rept., 1909. 



240 



DAIRY TECHNOLOGY 



produces a lactic acid and an alcoholic fermentation in 
milk. Certain organisms may be necessary for the de- 
velopment of the typical kefir flavor. 

Hammarsten shows the changes brought about in cows' 
milk, by this fermentation, in the following table: 



CHEMICAL ANALYSIS OF KEFIR. 





Two days 
old. 


Four days 
old. 


Six days 
old. 


Casein 


2.570 

0.425 
0.071 
3.700 
3.619 
0.641 
0.665 
. 230 


2.586 
0.405 
o.oSg 
2.238 
3-630 
0.624 
0.832 
0.810 


2.564 
0.390 
0. 120 


Lactalbumen 

Peptones 


Lactose 


1.670 
3.628 
0.630 
0.900 
I . 100 


Fat 


Ash 


Lactic acid 

Alcohol 







As indicated in the table, the only constituent of the 
milk appreciably affected is the lactose. By its fermen- 
tation, lactic acid, alcohol and carbon dioxide are formed. 
The physical condition of the casein is changed, and it 
may be more easily digestible because of its finely divided 
condition. 

The following directions are given for making kelir 
when the grains are obtainable. Soak the grains in warm 
water to soften them, changing the water several times. 
The grains are ready for use when they become gelatinous 
and whitish and rise to the surface. The grains are then 
added to bottles of pasteurized milk held at a tempera- 
ture of 57° to 60° F., and stirred or shaken occasionally. 
After 8 to 10 hours, the grains are strained out and the 
milk put into tightly stoppered bottles. The fermenta- 
tion is continued at the same temperature! and the bottles 
shaken occasionally to prevent the formation of hard 



FERMENTED MILKS 



241 



lumps of curd. After about twenty-four hours, the kefir 
is ready for use. The relative amounts of alcohol and 
lactic acid are dependent upon the temperature of fer- 
mentation. A high temperature favors the alcoholic 
fermentation and a slightly low temperature favors lactic- 
acid fermentation. 

The grains are used merely to start the fermenta 
tion. After their removal, the process continues with 
out their aid. The grains may be washed free from 
curd, dried and laid aside until wanted again. In their 
dry state, they are said to retain their vitality for several 
years. 

Kumiss. — When explorers and missionaries first visited 
the plains of European Russia and central and south- 
western Asia, they found the native nomadic tribes living 
to a large extent on a fermented milk now known as kumiss. 
This food was prepared from mares' milk. It is said that 
the proper fermentation was induced by the addition to 
the fresh milk of pieces of decaying flesh or vegetable 
matter. These tribes are great horsemen, and they have 
developed mares that give an unusually large quantity 
of milk. 

Mare's milk is lower in nutritive value than cows' milk, 
as the following table shows : ^ 

AVERAGE COMPOSITION OF COWS' MILK AND MARES- 
MILK. 





Water. 


Fat. 


Sugar. 


Casein. 


Albumen. 


Ash. 


Cow 

Mare 


Per cent. 
87.10 
90.06 


Per cent. 
I .09 


Per cent. 

4-75 
6.6s 


Per cent. 
3.00 


Per cent. 
0.40 


Per cent. 
0-75 


I . 


89 


0.31 



1 Richmond — Dairy Chemistry. 



242 



DAIRY TECHNOLOGY 



The composition of kumiss varies somewhat with the 
age, the rapidity of the fermentation, and the nature and 
extent of contamination with extraneous organisms. 

COMPOSITION OF KUMISS MADE FROM MARES' MILK.i 





One day 
old. 


Eight days 
old. 


Twenty-two 
days Old. 


Water 

Alcohol 

Lactic acid 


Per cent. 

91-43 
2.67 
0.77 
1-63 
0.77 
0. 25 
0.98 
1. 16 
0-3S 


Per cent. 
92. 12 

2 93 
1.08 
0.50 
0.85 
0.27 
0.76 
I. 12 
0.3s 


Per cent. 
92.07 
2.98 
1.27 
0.23 
0.83 
0. 24 
0.77 
1.30 
0-35 


Sugar 


Casein 


Albumen 


Albumose 


Fat 


Ash 





The fermentative changes in kumiss are very similar 
to those in kefir. The main difference between these two 
products is the origin of the milk. 

American Kefir or Kumiss. — Several dairy companies 
that cater to fancy city trade make a fermented milk and 
market it under the name kefir or kumiss. This product 
is, strictly speaking, not kumiss, because it is made of 
cows' milk instead of mares' milk. Nor is it kefir, because 
this latter product is the result of fermentation induced by 
kefir grains. However, the prefix "American" might be 
used to distinguish it from that of Asiatic origin. This 
American product is hygienic, being prepared from sanitary 
milk and fermented by carefully selected organisms. 

The best results are secured by inducing an alcoholic 
fermentation in good buttermilk. The use of buttermilk 
insures a finely di"/ided casein and a smooth, homogeneous 
product. 

For the alcoholic fermentation, ordinary bread yeast 

* Richmond — Dairy Chemistry. 



FERMENTED MILKS 243 

may be used ; but this yeast cannot ferment lactose, hence 
cane sugar must be added to the milk. The yeast may be 
added directly to the buttermilk, but better results are se- 
cured as follows : To four ounces of boiled water, add about 
ten grams of cane sugar and one third of a yeast cake. Do 
not add the yeast till water is cooled. Keep in a warm 
place (70° to 80° F.) over night, or for about ten hours. 
This produces an active culture of the yeast. To each 
quart bottle of buttermilk add 15 grams of cane sugar 
and 2 c.c. of yeast culture. Cap the bottles with patent 
stoppers or other tight caps that will withstand gas devel- 
opment within the bottle. Keep at a temperature of about 
60° F. for from three to four days with occasional shaking 
to break up the curd. At the end of this time, the prod- 
uct will be ready for use. Fermentation at a high tem- 
perature, and continued for too long a time, produces a 
strong undesirable flavor. The amount of alcohol and 
carbon dioxide developed depends upon the amount of 
sugar added to the buttermilk. The theoretical quantity 
of alcohol formed is about one half the Cjuantity of sugar 
fermented. The carbon dioxide, rather than the alcohol, 
is the desirable product of the yeast fermentation. The 
quantity of sugar to be added is governed by the quantity 
of carbon dioxide desired. Fifteen grams of sugar in one 
quart of buttermilk (i per cent of sugar) produces the 
desirable effervescence, and the sharp taste of charged 
water, but will not cause an excess of gas. 

A similar product may be made from skim milk instead 
of buttermilk. In this case the milk should be pasteurized 
and a slightly larger percentage of sugar (two to three per 
cent) be used. This product lacks the sharp acid flavor 
of the buttermilk product, but has the pleasant gas- 
charged flavor. 



244 DAIRY TECHNOLOGY 

Yoghurt. — The people inhabiting the countries border- 
ing the eastern end of the Mediterranean prepare a milk 
that is quite different from those previously mentioned. 
Yoghurt is a thick curdled milk, high in acid, but contain- 
ing little or no alcohol. It is prepared from goats', buf- 
falos', and cows' milk. This is usually boiled, and some- 
times the boiling is continued until the milk is evaporated 
to one half its original volume. In the latter case the 
product has the consistency of pudding and instead of 
being used as a drink, is eaten, sometimes with the addi- 
tion of dates, bread or other food. 

The different people of this region have various names ^ 
for their prepared milks, but the products are all very 
similar. The Turks use the names "yoghurt," " yahourth " 
and " jugurt"; the Balkan people, " kisselo melko"; the 
Armenians, "mazum"; the Sardinians, "gioddu"; and 
the Egyptians, '' leben " or " leben raib." 

Several investigators have studied these fermented milks 
from a bacterial standpoint, and have isolated certain 
organisms and applied various names to them. But the 
opinion generally held by investigators, at the present 
time, is that the various organisms necessary for the pro- 
duction of milks of the yoghurt class, all may be included 
under the name Bacillus bulgaricus. 

This Bacillus bulgaricus has a very characteristic action 
when grown in milk. In a few hours at the optimum 
temperature (about ioo° F.) a curd is formed that is rather 
soft, sometimes shiny, and does not settle to the bottom or 
" whey off " upon long standing. The acidity of the milk 
may reach two per cent in twenty hours and three per cent 
after several days. 

1 U. S. Depl. of Agr., Bu. An. Iiid., An. Rept., 1909. 



FERMENTED MILKS 245 

Ropy Milk. — Fermentation of milk by Streptococcus 
hollandicus produces a slightly sour milk with a thick 
slimy consistency. 

In Norway and Sweden, and also in Finland, it is a 
commercial article, and is brought into the towns by the 
peasants to be sold in much the same way as butter is 
brought into the towns to be sold here, only on not so large 
a scale. In Holland it is called " langewej," and is there 
used chiefly as a starter to control the gassy fermentation 
in the manufacture of Edam cheese. 

Moscow Sour Cream. — This product is made from cream 
that has undergone a good acid fermentation. Having been 
thoroughly mixed in the starter, the mass is allowed to stand 
undisturbed at a temperature between 77° and 90° F., for 
six or more hours until ripe. When it reaches such a 
point that an acid flavor can just be detected, it is taken 
to a cold room or ice box. While it is being cooled all 
the cream thickens to a uniform mass without clots, and 
has a pleasant, acid taste. This sour cream is thick 
and solid. It may be cut with a knife like butter. The 
fermentation is effected in wooden or glass vessels, never 
in metal vessels. The latter would give it a metalHc taste. 
There is no need whatever to press the sour cream, for the 
whole of the cream is used without any separation of whey. 
The sour cream must not be agitated. When putting it 
into boxes or casks, care must be taken to put it in layer on 
layer. It can be quite safely transported in wooden boxes 
lined with parchment. As the sour cream is solid, there is 
no necessity to add any preservative. With a temperature 
in the cellar of 48° to 55° F. when the casks or cases are 
put in, the sour cream will keep for three or four months. 

There are some milk preparations which are allied to 
fermented milks, but which have undergone no special 



246 DAIRY TECHNOLOGY 

fermentation. Carbonated milk and Devonshire cream 
come in this class. 

Clotted or Devonshire Cream. — Devonshire cream used 
to be a special product of the West of England. How- 
ever, it can be made anywhere, provided the milk be rich 
and the treatment correct. The milk should be strained 
while warm into the pans in which it is to be scalded. 
These pans are from 6 to 8 inches deep and about eighteen 
inches in diameter, and are made to fit into a pan of water, 
which in turn fits on to a stove. 

The milk sets for twelve hours until the cream has risen. 
Then the fire is lighted and the cream is scalded. The 
water jacket prevents the temperature rising too high, 
which would give a cooked taste to the product ; and when 
the process is complete, handles on the side of the pan 
enable it to be Hfted off easily. The great art in scalding 
is to get a thick unbroken layer of cream on the surface 
with a wrinkled, yellow appearance. The heating should 
be done slowly, until a temperature of from 180° to 
185° F. is attained, at the rate of about 2° per minute for 
an hour. 

The cooling is accomplished either by raking out the 
fire for slow cooling, or by setting the pan in cold water 
for quick cooling, after which the cream is ready for use 
or for putting into jars. For quick work, on a large scale, 
the cream is sometimes separated, and then a thick layer 
put back onto pans of separated milk, and then scalded. 
The cream must be scalded on the milk, as it cannot be 
done satisfactorily alone. Both the milk and the cream 
keep well, because the process is equivalent to pasteuri- 
zation. For small quantities, any kind of a pan on any 
kind of a stove will do if conditions are observed and the 
process carried out carefully. 



FERMENTED MILKS 247 

Carbonated Milk. — Van Slyke and Bosworth,^ in 
making a study of the chemical changes in kumiss made 
from cows' milk, noticed that lactic acid formed in it much 
more slowly than in ordinary milk. This was found to 
be due to the action of carbon-dioxide gas under pressure. 

A series of experiments was conducted in order to ascer- 
tain the effect of carbon dioxide under pressure upon the 
development of lactic acid in milk. The results of these 
experiments are reported in the New York Geneva Sta- 
tion Bulletin 292. 

The milk used was (i) fresh, separator skim milk; (2) 
fresh whole milk, drawn and handled under good hygienic 
conditions; (3) fresh skim milk pasteurized at 185° F., 
and (4) fresh whole milk pasteurized at 185° F. 

The pressures of gas employed were 71, 150 and 175 
pounds per square inch. 

The most effective method of treating the milk was to 
charge it with carbon-dioxide gas at the desired pressure 
in a tank such as is used in bottling establishments in 
preparing carbonated drinks, and then to fill into bottles. 

The carbonated milk was kept at temperatures varying 
from 35° to 70° F. 

Pasteurized milk, carbonated, kept for five months 
with little increase of acidity. Fresh, raw whole milk, 
carbonated, kept in one experiment for about the same 
length of time. 

Carbonated milk makes a pleasant beverage and may 
find practical use as a healthful drink. It may also be 
found useful for invalids and children. 

The effect of carbonating milk upon organisms other 
than lactic has not yet been studied. 

Milk carbonated under a pressure of 70 pounds comes 

1 Geneva, N. V., Bui. 



248 DAIRY TECHNOLOGY 

from the bottle as a foamy mass, more or less like kumiss 
that is two or three days old. It has a slightly acid, 
pleasant flavor, due to the carbon dioxide, and tastes some- 
what more saline than ordinary milk. In the case of car- 
bonated milk pasteurized at 185° F., there is something 
of a " cooked " taste. Though the cream separates in 
the bottle, it is thoroughly remixed by a little shaking as 
the milk comes from the bottle, and there is no appearance 
of separate particles of cream. All who have had occa- 
sion to test the quality of carbonated milk as a beverage 
agree that it is a pleasant drink. Milk bottled under a 
pressure of 150 pounds of carbon dioxide is about the con- 
sistency of whipped cream. On standing a short time, 
it changes into a readily drinkable condition. From the 
authors' experience it would seem that carbonated milk 
might be made a popular beverage. 



CHAPTER XXIX. 

CONDENSED AND EVAPORATED MILK. 

The purpose of condensing milk is twofold: to improve 
its keeping property, and to lessen its bulk. These two 
oijjects must be attained without changing any of the 
essential properties of any of the milk components and 
still have these components soluble again when water is 
added. In this latter form, it should have all the flavor 
and appearance of fresh normal milk. 

Extent of the Industry. — The United States Census 
Report of 1905 reports 81 milk-condensing factories in 
the United States during that year. These factories 
were distributed over 17 states and manufactured about 
320,000,000 pounds of condensed milk. During the past 
six years this industry has been making very rapid strides. 
The number of condenseries has about doubled, and the 
pounds of finished product have reached the half-billion 
mark. 

The consumption of condensed milk is increasing rapidly, 
not only in the tropic and arctic regions, on shipboard, in 
mining and lumber camps where little or no milk is pro- 
duced, but also in our local home markets. The ice-cream 
industry is responsible for a considerable demand on the 
condensed milk supply. The baker and candy maker also 
use their share, and many housewives, especially in our 
large cities, find the canned product more reliable than that 
furnished daily by the city milk plant. This is true mainly 
in cities that have had no pure milk crusade. 

249 



250 DAIRY TECHNOLOGY 

United States Standards. — In the Federal Food and 
Drug Act that went into effect January i, 1907, condensed 
and evaporated milk are classified as follows: 

" Condensed Milk, Evaporated Milk, is milk from which 
a considerable portion of water has been evaporated and 
contains not less than twenty-eight (28) per cent of milk 
solids of which not less than twenty-seven and five-tenths 
(27.5) per cent is milk fat. 

'^Sweetened Condensed Milk is milk from which a con- 
siderable portion of water has been evaporated and to 
which sugar (sucrose) has been added, and contains not less 
than twenty-eight (28) per cent of milk solids, of which not 
less than twenty-seven and five-tenths (27.5) per cent is 
milk fat. 

" Condensed Skim Milk is skim milk from which a con- 
siderable portion of water has been evaporated." 

Evaporated milk is unsweetened condensed milk put 
up in hermetically sealed cans holding from six and one- 
half to twenty ounces, and also in quart and gallon cans. 
This product is somewhat deceiving to the eye. It appears 
to be very thick and rich, while, as a matter of fact, the milk 
is condensed only from about two or two and one-half parts 
of the fresh milk, to one of evaporated milk. It contains 
no cane sugar to act as a preservative, but is steriHzed by 
steam under pressure. 

Plain condensed milk is made in a similar manner, but 
is not sterilized. It is usually marketed in ordinary milk 
cans in the same general manner as fresh milk. It will 
keep in good condition for from ten to thirty days, if kept at 
a low temperature. It is intended for early consumption, 
and is used by hotels, restaurants, and candy and ice-cream 
makers, as starter milk in butter factories, and to some 
extent in private houses. 

Sweetened condensed milk is that to which sufficient 



CONDENSED AND EVAPORATED MILK 251 

sugar has been added to prevent fermentation. This is a 
very thick syrupy product containing about forty per cent 
cane sugar and twenty-eight to thirty-six per cent milk 
soHds. 

Quality of Raw Product. — The quaUty requirements 
of milk for condensing purposes, especially for evaporated 
milk, are higher than for any other purpose. The conden- 
sary usually keeps an inspector on the road all the time, 
and the patrons are required to follow his suggestions. 
Some condenseries require all patrons to use a certain style 
of milk cooler, and require the milk to be below a certain 
temperature — 55° to 60° F. — when delivered at the fac- 
tory. Bad odors or dirt in the milk is not tolerated. 

The condensery operator claims that milk from cows fed 
on silage, brewers' grain and similar feeds, curdles much 
more readily than that from cows not fed on these feeds; 
hence where evaporated milk is made, such feeds are usually 
forbidden. In some instances these feeds are permitted, 
but the time of feeding and the amount fed are restricted. 

The following rules and regulations are enforced by the 
Pacific Coast Condensed Milk Company: 

" I. All cows must be healthy and in good flesh at all 
times, be milked at regular hours, morning and evening, 
and in a cleanly manner. They must be kindly treated 
and no milk will be accepted from cows that are overheated 
or excited from any cause. 

2. The milk must be cooled and aerated immediately 
after milking, and put into tin cans which have been rinsed 
in clean, cold water. Both milk and cans must be kept' 
where they will be free from filth or bad odors. 

3. The cans of milk must be left with the lids off, in 
cold water to prevent rise in temperature, until ready for 
delivery. They should be covered with wire screen or clean 
cloth to prevent foreign substances from getting into the 
milk. 



252 DAIRY TECHNOLOGY 

4. By the use of coolers milk can be reduced immediately 
to within a few degrees of the temperature of the water 
used. Milk higher than 65° F. will not be accepted at 
the factory. 

5. Tin pails only are to be used to milk in, and they must 
be thoroughly washed and scalded every time they are 
used, and allowed to dry in the open air, in the sun if pos- 
sible, and must not be used for any other purpose. 

6. The night's and morning's milk shall not be mixed, 
and no milk shall be kept over to be delivered at a sub- 
sequent time. 

7. The evening's milk must be kept at or below a tem- 
perature of 55° F., and out of contact with dirt or bad odors. 

8. When the cans in which the milk is transported to 
the factory are not in use, they shall be turned down on a 
rack with the covers off, except only when in transit. 

9. All milk, including the strippings, shall be delivered. 
No milk shall be delivered which is taken from cows that 
have calved within twelve days, nor from any cow that is 
to calve within thirty days. 

10. If there is good reason to suspect that water has 
been added, or cream removed, or that milk has not been 
properly cooled, or that it has been injured by carelessness 
or from filth, or if the cans are filthy, such milk will be 
refused. 

1 1 . Cows must not be allowed to eat sour, noxious grasses 
and weeds, or other objectionable food. No still or brewers' 
grains, or slops, sorghum or glucose refuse, cabbages, 
ensilage or other damaged or decayed food of any kind 
shall be fed under any circumstances, and sugar beets, tur- 
iiips and red carrots only in small quantities and soon after 
milking. 

12. Stables and sheds where cows are kept must be clean 
and free from foul odors. 

13. Our inspector shall have the right to visit the prem- 
ises of our patrons at any time, and all suggestions made 
by him must be carefully carried out. 

14. We shall refuse milk from anyone violating these 
rules." 



CONDENSED AND EVAPOIL\TED MILK 253 

The Condensing Process. — The condensing of milk 
has been developed to its present state of perfection only 
by the expenditure of much time and money in experi- 
menting. To be a high-grade marketable product, the 
milk must be condensed under very exact conditions, 
and brought to the proper degree of condensation. Milk 



^ 




Fio. 47. — Milk condensing pan. 

not properly condensed may have a marked cooked flavor, 
or be curdy, or contain lumps of butter, instead of being 
smooth and homogeneous. 

To avoid the cooked flavor and to prevent the milk 
from burning to the inside of the condenser it is necessary 
to condense or evaporate at a low temperature. 

The boiling-point of milk, like that of other liquids, 
varies according to atmospheric pressure. The boiling- 



254 DAIRY TECHNOLOGY 

point of milk is a little higher than that of water, viz., 
about 214° F. At such a temperature, during so long a 
time as is necessary for evaporation, the milk assumes a 
marked cooked flavor, and some natural characteristics 
of the milk components change. For instance, the sugar 
caramelizes, the fat melts into oil so as to make remixing 
difficult, some albumen coagulates, and a portion of the 
calcium phosphate salts separates from the casein. If the 
atmospheric pressure is reduced so as to bring the boiling- 
point to from 120° to 130° F., evaporation takes place and 
the undesirable changes incident to higher heat are absent. 
This is effected in the apparatus known as a vacuum pan. 
Such a pan consists usually of four chief parts: 

1. The pan or kettle, which holds the milk and which 
is usually lined with bright copper. 

2. A steam jacket, around the pan or steam coils, or 
both, to supply the heat necessary for evaporation. 

3. The condenser, connecting with the top part of the 
pan for condensing the steam and creating additional 
vacuum. Cold water constantly circulates through the 
condenser. 

4. The vacuum pump, used for reducing the atmospheric 
pressure in the pan by pumping out the air and for remov- 
ing steam and water in case a wet vacuum is used. If 
a dry vacuum is used, the pump removes only the air, 
and the water flows out by its own gravity. 

So far as known, Mr. Gail Borden of the United States 
was the inventor of the vacuum method of milk conden- 
sation. A patent was taken out by him in the United 
States in 1856. One objection to this first condensed 
milk was that it would keep only a few weeks. 

Mr. C. A. Page, then United States consul at Zurich, 
improved the Borden method by adding sugar. This 



CONDENSED AND EVAPORATED MILK 255 

made the concentration of nutrients so great that bacteria 
did not develop in it, even if constantly exposed to the air. 
Mr. Page started a factory in Switzerland. In 1866 he 
was succeeded by the Anglo-Swiss Milk Company, which 
located a large factory on Lake Zug in the canton of that 
name. This company prospered and so far as known still 
exists and has branches in the United States, Germany, 
England and Switzerland. It suppHed practically the whole 
of Europe with condensed milk. The Borden Condensed 
Milk Company is one of the largest in this country. 

Before the milk is put into the vacuum pan, it is heated 
and run through a clarifier to remove all physical dirt 
and some of the objectionable odors. Then it is passed 
on to the vacuum pan, where the condensation takes 
place. 

Enough air is pumped out of the vacuum pan so that 
it will show a vacuum or air pressure of 24 to 28 inches 
as measured by a mercurial column vacuum gauge. In 
such a vacuum, milk boils at a temperature of from 105° 
to 135° F. It is very essential to keep the vacuum pump 
working uniformly in order to maintain a constant vacuum. 
Should the vacuum be greatly lessened, evaporation would 
cease, the temperature of the milk would rise, and the 
entire batch of milk might be spoiled. Condensation is 
continued until a sample drawn from the pan shows the 
proper degree of concentration as determined by a Baume 
hydrometer. 

Degree of Concentration. — This is undoubtedly the 
most important point in the process. When concentrated 
too much, the result may be curdled milk. When not 
sufficiently concentrated, the fat separates and may churn 
in subsequent processes. In either case the commercial 
value of the product is greatly lessened. 



256 



DAIRY TECHNOLOGY 



By concentrating the milk by evaporation of water the 
per cent of acid and other non-volatile chemicals are in- 
creased. This may be illustrated as follows: Supposing 
the milk to be condensed contained 0.2 per cent acid, and 
this milk was condensed to one half its volume, the per 
cent acid contained in the finished product would be twice 
its original per cent, or 0.4 per cent. By further conden- 
sation, the per cent acid will increase proportionately. 
The great importance of having milk with a low acid con- 
tent for condensed milk is readily understood. This in- 
creased per cent of acidity after condensation and increased 
heat during the condensation period are likely to cause 
the milk to curdle and become lumpy. This latter is 
very undesirable. Condensed milk should have a uni- 
formly smooth body. If it has not, the trade rejects it. 
It is possible that other components of milk affect the 
properties of the finished product similarly to the acid on 
concentration and heating. 

The following table^ shows the results of evaporating 
fresh milk to different degrees of concentration. 



Lot No. 



Concentration. 


1.58 




r-74 




1.9 




1.99 




2. II 




2.2s 





Per cent of acid. 



0.30 

0.34 
0.40 

0.43 
0.48 

0.54 



Condition of casein. 



Not precipitated. 
Not precipitated. 
Not precipitated. 
Not precipitated. 
Small lumps of curd. 
Large lumps of curd. 



The different lots of evaporated milk were made from 
the same batch of fresh milk. 

Another kind of undesirable condensed milk is that 
which is churned. It is important that the butter fat be 
properly emulsified with the remainder of the milk com- 

^ Indiana Bui. 143. 



CONDENSED AND EVAPORATED MILK 



!57 



ponents. Butter lumps in the condensed milk are due 
chiefly to the condensed milk being too thin when put into 
the shaker. This condition of the fat may also partially 
be caused by allowing the condensed milk to cool without 
shaking immediately after it has been taken out of the steri- 
lizing oven. Except in case of accidents to machinery, this 
factor seldom enters in as a cause of churned condensed milk. 

A third factor causing losses to the condense ries is im- 
proper sterilization. Even though the milk is sterilized 
in steam-pressure ovens, some ferments are not destroyed. 
In order to be sure that the sterilization has been complete, 
the sealed cans containing the condensed milk are put into 
a testing room. The temperature of this room is kept uni- 
form and high enough for rapid growth of germs. If any 
ferments remain, the cans show it in a few days by bulging 
or distended sides. This latter is due to the development 
of gas. The cans showing this characteristic are discarded. 

Hunziker ^ carried on some experiments in connection 
with the Indiana Condensed Milk Company at Sheridan, 
Indiana, to demonstrate the effect of different degrees of 
concentration on the marketable properties of evaporated 
milk. The results are tabulated below: 



JUNE EXPERIMENT. 



No. 


Concentration. 


Milk solids, 
per cent. 


Condition of sample one month after 
manufacture. 


I 


I.6l : I 


20.40 


Fat separated and churned, no 
curd. 


2 

3 
4 


1 .96 : I 
2 . 00 : I 
2 . 20 : I 


24.87 
25 38 
28.02 


Smooth, no separation, no curd. 
Smooth, no separation, no curd. 
Curdy, lumps of curd, fat not 


5 


2.52 : I 


3199 


separated. 
Curdy, lumps of curd, fat not 
separated. 



Total solids in fresh milk, 12 .68 per cent. 

Acidity in fresh milk 0.16 per cent 

1 Indiana Bid. 143. 



258 



DAIRY TECHNOLOGY 



AUGUST EXPERIMENT. 



No. 


Concentration. 


Milk solids, 
per cent. 


Condition of sample one month after 
manufacture. 


I 


1.94 : I 


22.79 


Fat separated and churned, no 
curd. 


2 


2. II : I 


24.81 


Fat separated and churned, no 
curd. 


3 


2.21 : I 


26.01 


Smooth, no separation, no curd. 


4 


2.33 : I 


27-33 


Curdy, small lumps of curd, no 
separation. 


5 


2.5 : I 


29-37 


Curdy, lumps of curd, no sepa- 
ration. 



Total solids in fresh milk, 11 .75 per cent. 
Acidity in fresh milk, 0.12 per cent. 



NOVEMBER EXPERIMENT. 



No. 


Concentration. 


Milk solids, 
per cent. 


Condition of sample one month after 
manufacture. 


I 


1.58 : I 


21.12 


Fat separated and churned, no 
curd. 


2 


1 . 74 : I 


23-25 


Fat separated and churned, no 
curd. 


3 


1.9 : I 


25.48 


Smooth, no separation, no curd. 


4 


1.99 : I 


26.62 


Smooth, no separation, no curd. 


5 


2. II : I 


28.23 


Curdy, small lumps of curd, no 
separation. 


6 


2.25 : I 


30.10 


Curdy, lumps of curd, no sepa- 
ration. 



Total solids in fresh milk, 13 .40 per cent. 
Acidity in fresh milk, 0.17 per cent. 

The following conclusions are drawn by the investigator: 

" These experiments show that, in this particular factory, 
a hard curd is formed in the evaporated milk when the con- 
centration is carried as far as 28 per cent solids. They 
further show that there is a distinct difference in the be- 
havior of the milk at different times of the year. In spring 
or early summer there is a greater tendency for curdy milk 
than later in the season. It has been experimentally 



CONDENSED AND EVAPORATED MILK 259 

shown that, in some locahties and at certain seasons of 
the year, a marketable evaporated milk cannot be made 
when the product is condensed sufficiently to contain over 
24 per cent solids." 

When the milk is drawn from the condensing pan it is 
ready to be canned, but as this requires some time, the 
milk is first cooled to prevent acid development and other 
fermentations. The cooling is usually accomplished by 
means of a coil in a manner similar to that of cooling fresh 
milk in a city milk plant. The cooled milk is stored in 
sanitary tanks, drawn out a little at a time, and run into 
the can fillers, which are operated in a manner similar to 
the operation of the common milk-bottle filler. The can- 
ning process is completed with the soldering on of the 
tops. 

Sterilization. — This canned evaporated milk quickly 
undergoes fermentation unless absolutely sterilized. In 
order to effect sterilization it is necessary to heat the milk 
under steam pressure. The sterilizers used are similar in 
construction and principle to the autoclave used in the 
bacteriology laboratory, except that they are larger. They 
are so arranged that trucks loaded with cases of milk may 
be run into them on a track. 

The degree of heat employed and the duration of the 
heat exposure of the condensed milk are very important 
factors. Even perfectly sweet, normal milk curdles at a 
temperature of 269° F., and the more concentrated the 
milk the lower the temperature required to curdle it. 
There are other factors, such as the per cent of casein 
present, the relative amounts of the dififerent ash con- 
stituents, etc., which influence, to a greater or less degree, 
the curdling point of milk. Temperatures ranging from 
226° to 245° F. are used to sterilize condensed milk. 



26o 



DAIRY TECHNOLOGY 



The greater the degree of heat, and the longer the ex- 
posure, the more intense is the action on the condensed 
milk, and, therefore, the harder the coagulum formed. 
Since absolute steriUty of the milk is necessary, and since 
heat is the only agent that can be used to bring this con- 
dition about, the milk must be exposed to such degree of 
heat, and such duration of that heat as will accomplish 
complete sterilization. 

Shaking the Canned Milk. — The condensed milk hav- 
ing been sterilized in sealed cans, the next process in order 




Fig. 48. — Combined machine for sterilizing and shaking condensed milk. 



is the shaking of the cans to break any lumps of curd or 
fat that may have formed, and to insure a smooth, homo- 
geneous mixing of the fat. The shaking machine may be 
combined with the sterilizer or it may be a separate piece 
of apparatus. 

After the shaking process, the cans are placed in the 
testing room, or incubator, as it might be called, where 
they are kept at about blood heat for several days. If 
any live spores are present in the milk, they will germinate 



CONDENSED AND EVAPORATED MILK 



261 



and multiply rapidly at this high temperature. Any cans 
of milk that have fermented are readily detected on account 
of distended sides and are thrown out when the cans are 
removed from the store-room. The cans are so arranged 
that the oldest ones can be removed first. 

Composition of Evaporated Milk. — When milk is con- 
centrated in the ratio of two parts of fresh milk to one part 
of condensed milk, it is evident that the percentage of the 
various milk constituents in the evaporated product would 
be just double that in the fresh milk. 

The following, from Leach, is a fair example of a good 
quality of evaporated milk: 



Total 
solids. 


Water. 


Milk 
sugar. 


Proteids. 


Fat. 


Ash. 


Number 

of times 

condensed. 


28.16 


69.24 


9-8s 


8.66 


8.1 


i-SS 


2.2 



Composition of Sweetened Condensed Milk. — In the 

manufacture of sweetened condensed milk, the process 
employed is similar to that used in the production of 
evaporated milk. The great difference is the addition of 
cane sugar. This addition of cane sugar obviates the 
necessity for sterilization and hence enables the manu- 
facturer to omit that very delicate process. 

Another difference between evaporated and sweetened 
condensed milk is that the latter is carried to a greater 
degree of concentration, commonly 32 per cent of milk sohds 
and often more than this. When milk is too thin the sugar 
deposits in the bottom of the cans, and this greatly de- 
creases its commercial value. The greater the degree of 
concentration, the better are the keeping qualities. Thin 
milk is more prone to undergo fermentation than the highly 



262 



DAIRY TECHNOLOGY 



concentrated product. Hence we find sweetened con- 
densed milk usually concentrated in the proportion of two 
and three-fourths to one. 

The composition of this product varies between wide 
limits, but a fair example of a good quality of sweetened 
condensed milk is, according to Leach, as follows: 



Total 
solids. 


Water. 


Milk 
solids. 


Cane 
sugar. 


Milk 
sugar. 


Proteids. 


Fat. 


Ash. 


Number 
of times 
condensed. 


74.29 


25-71 


32.37 


41.92 


11.97 


8.46 


10.65 


I .29 


^■3 



Relatively Large Investment Needed. — The establish- 
ment and operation of a milk condensery is a much larger 
proposition than the manufacture of butter or cheese. 
More milk is also necessary within a given radius. A 
condensing plant is usually not very prosperous unless 
there is a milk supply of 50,000 pounds per day. An ex- 
pensive building and expensive machinery are required. 
A good supply of cold water is a requisite. Roughly speak- 
ing, a supply of ten times as much water as there is milk 
to be condensed should be assured. The steam required 
is also a large item. For each 1000 pounds of milk to be 
condensed per day, about six horse power of steam is 
needed. However, the profits are proportionately great, 
and a properly conducted factory with an ample supply 
of milk usually prospers. 

The large condensery finds it economical to use all 
possible labor-saving devices. Cases are nailed with a 
nailing machine and the labeling is done automatically. 
Cans are fed in at one end of the labeling machines, are 
carried along, a label is pasted on, and the cans are delivered 
at the other end directly into the shipping cases without 
further handling. 



CONDENSED AND EVAPORATED MILK 263 

However, milk condensing as a side line for the ice- 
cream manufacturer, city milk dealer, and creamery man 
has been adopted in a few instances. Machinery is on 
the market for condensing as small quantities as 250 to 
6000 pounds of fresh milk daily. This apparatus may be 
installed for about one thousand dollars, and may be of 
value in turning surplus milk into bulk, condensed milk, 
provided a market for this product is assured. 



CHAPTER XXX. 

MILK POWDER. 

Some economist has calculated that because milk is 
nearly nine-tenths water the transportation of this natural 
product costs ten times as much as it should. Figuring 
on a basis of 2,000,000 quarts per day as New York City's 
daily milk supply, he finds that the people are losing about 
$17,500 per day. This is the expense of the shipping, 
carting, hauling, bottling, etc., of the watery portion of the 
milk. This means an annual loss, in N. Y., of $6,500,000 
from this source. On this basis the national loss is esti- 
mated to be about $63,000,000 per annum. 

Without accepting or discussing the accuracy of the 
above calculations, or the necessity for bringing to the 
consumer a natural, uncondensed product, we must admit 
that there are many places where a good concentrated 
milk could replace the bulky natural product, and where 
milk in that form would be and is used when the natu- 
ral milk cannot possibly be utilized. 

One pound of condensed or evaporated milk represents 
but two to two and one-half pounds of raw milk, while one 
pound of milk powder represents about eight pounds of 
natural milk. 

Advantages of Milk Powder. — The chief desirable 
results of reducing milk to powder may be summed up as 
follows. This refers to milk powder made from skim milk. 

I. It is concentrated, making cost of package and trans- 
portation the minimum. 

264 



MILK POWDER 265 

2. It has good keeping properties. Germs do not multi- 
ply in skim-milk powder, even at ordinary room temper- 
ature. 

3. It is a dry substance, making it handy to carry on 
long sea and land journeys. 

4. A milk of any consistency or richness can be made 
from it by adding water, making it of special value in 
baking, candy making, and ice-cream manufacture. 

History and Development of Milk Desiccation. — The 
problem of inventing a proper system of milk desiccation 
has been worked upon to some extent for more than a 
century, but more especially during the past sixty years. 

As early as 1810, a man by the name of Appert produced 
milk tablets, but they did not become of any commercial 
importance. In 1856 a Mr. Grimwade published a method 
of manufacturing dried milk. It consisted of sweetening 
the milk with sugar and at the same time adding carbonate 
of soda. These substances were added to produce granu- 
lation in the latter stages of dryness. This mixture was 
put into a jacketed pan, which was pivoted and kept in 
constant motion during time of drying. The surrounding 
jacket was filled with hot water, the temperature of which 
never went above 1 29° F. When the mixture became 
pasty, it was poured off into smaller pans, stirred and 
dried still more; then this paste or dough was passed 
between marble rollers and pressed into thin sheets. These 
sheets were then dried with hot air and finally ground to 
powder. Later the vacuum pan was used in condensing. 

Another process consisted of precipitating the casein 
and fat by the use of acetic acid or rennet. This curd 
was drained and then dried on plates at a temperature 
of between 120° F. and 160° F. The solubility of this 
powder was restored by adding a little soda. The widely 



266 DAIRY TECHNOLOGY 

advertised " plasmon " is made in this manner. The 
process was not economical as some of the milk nutrients 
(sugar and albumen) were lost in the whey. This sub- 
stance (plasmon) does not contain all of the elements 
of milk, and therefore could not serve as a substitute for 
milk. 

Milk powder became of commercial importance when 
the Just-Hatmaker machine and process of drying came 
into use. The patent for this process is dated May 23, 
1902. The desiccating machine consists of two large 
revolving poUshed rollers or cylinders placed parallel in 
a frame. The rollers are about sixty inches in length 
and twenty-eight inches in diameter. They revolve in 
opposite directions at about six revolutions per minute. 
Steam is introduced through the end of the spindle and 
a pressure of 40 pounds is maintained. This insures a 
constant temperature of 285° F. The condensed steam 
is removed at the other end at the corresponding place. 

The two cylinders are about one eighth of an inch apart. 
When the milk falls and spreads in thin sheets on these 
revolving hot cylinders, it dries almost instantaneously. 
The residue remains on the cylinders and is scraped off in 
a powder-like consistency by means of scrapers attached 
to the machine. The powder is now passed through a 
fine sieve and is then ready for packing. 

Drs. George Doellner, Buttler and J. Maggo have all 
patented homogenization of the milk previous to dry- 
ing. It is claimed that this improves the keeping prop- 
erty. The process reduces the size of the fat globules to 
such an extent that decomposition proceeds very slowly. 
This latter, however, is by no means a well-established fact. 

Dr. Eckenberg of Sweden has invented an ingenious 
system of milk drying at a low temperature and in vacuum. 



MILK POWDER 267 

The machine consists of a cylindrical device inside of 
which rotates slowly a nickel-plated drum. The interior 
of the drum is steam-heated. An air pump creates a 
vacuum. The milk is put into the bottom. The ro- 
tating drum picks up a film of the milk and dries it prac- 
tically instantaneously, although the temperature is only 
about 104° F. 

Scrapers take off the dried milk from the drum and 
discharge it into a receiver on the side, through valves 
which open and close intermittently. 

The Modern Method. — A description of the latest 
and, so far as known, the most successful method of milk 
desiccation is given by L. C. Merrell in a paper read 
before the Syracuse Section of the American Chemical 
Society, 1908. 

" Fresh whole milk is drawn into a vacuum pan and a 
portion of its water removed. This condensation is halted 
while the milk is still in a fluid condition and before any 
of the milk albumen has been cooked on to the walls of 
the vacuum chamber. The milk is then drawn from the 
vacuum pan and sprayed into a current of hot air. The 
moisture of the milk is instantly absorbed by the air and 
the particles of milk solids fall like snow. Upon exami- 
nation, they are found to contain less than two per cent of 
moisture. The hotter the air is, the more rapid the dry- 
ing effect and the less danger there is of injuring the milk 
solids by heat. 

" This method of desiccation does not destroy the globu- 
lar condition of the butter fat, it does not burn the milk 
sugar, nor does it coagulate the albumen of the milk. It 
is not necessary to neutralize the acidity of the milk, for 
the moisture is removed so cjuickly that there is no chance 
for chemical action, and neither the casein nor the albumen 
is effected in any way by the concentration of the acid. 
The difficult pasty condition of the milk solids is passed 
while the milk particle is suspended in the air and not in 



268 DAIRY TECHNOLOGY 

contact with heated metal. As nearly as I can estimate, 
one pint of milk presents about two acres of surface when 
sprayed into the air. The individual dried particles are 
from one two-thousandth to one ten- thousandth of an 
inch in diameter. 

" No bacterial action has been discovered in milk powder 
containing less than 3 per cent moisture, and no chemical 
deterioration takes place. It is, therefore, evident that 
the milk powder product described above fulfills my 
definition of an ideal preserved milk, for decomposition is 
prevented merely by dryness and without the use of pre- 
servative substances and without changing the chemical 
composition of the milk. This whole milk powder is in 
use in place of fresh milk at several of the United States 
soldiers' homes and military posts as well as in the navy. 
It has been subjected to the most exhaustive tests by the 
United States Department of Agriculture, Bureau of Chem- 
istry, and by the Experiment Stations of different states. 
The Pacific fleet carried a ton of it around the Horn under 
an absolute guaranty as to keeping quality and has since 
re-ordered largely. A 10 cent package makes one and a 
half quarts of milk, at $o.o6f a quart. With these re- 
sults in mind it is not too much to assume that the reduc- 
tion of milk to powder offers a satisfactory solution of the 
universal milk question." 

Use of Milk Powder. — This product is being used to 
replace fresh milk by bakers, confectioners and ice-cream 
manufacturers. It was used as a food by the Shackleton 
South Polar expedition, and was one of the main foods of 
the party that reached the magnetic pole. 

The authors ^ have found milk powder to be of great 
value for starter-making purposes in creameries so located 
that a supply of fresh milk is not easily obtainable. 

The milk powder was dissolved in pure water, making 
a lo-per-cent solution. Pasteurization, inoculation, ripen- 

^ So. Dakota Bid., No. 123. 



MILK POWDER 



269 



ing, etc., of the milk-powder starters were all carried on 
in the same manner as when fresh-milk starters were 
made and the results secured by the use of milk-powder 
starters were as good as those when fresh-milk starters 
were used. 

Milk powder is used in the preparation of commercial 
cultures of lactic-acid bacteria, the culture material being 
mixed with sterile-milk powder, bottled and distributed 
for use in butter and cheese factories. In this medium 
the lactic bacteria retain their vitahty for more than a 
year. 

Composition. — Three kinds of milk powders are manu- 
factured: whole-milk powder, half-skimmed-milk powder 
and skimmed-milk powder. The butter fat in the whole- 
milk powder interferes with its keeping properties. 

The composition of these dried milks is as follows: 



Casein 

Milk sugar . . . 
Butter fat ... . 
Milk salts (ash). 
Moisture 



Whole milk. 



Per cent. 

26.92 

36.48 

29 . 20 

6.00 

I 40 



Half-skimmed. 



Per cent 

39.70 

15.10 

6.90 

5 00 



Skimmed. 



Per cent. 

37.00 

47.00 

1 .00 

8.00 

7.00 



Whey Powder or Dried Whey. — Whey is reduced to 
a powder by exactly the same process as that employed 
in the reduction of milk to powder. This powder is 
used in the diet of infants and invalids, in cases where 
the presence of casein Interferes with proper digestion. 
Many dietary formulas call for whey as one of the ingre- 
dients. Fresh whey is not always obtainable, but whey 
powder may be kept on hand at all times and Is ready for 
use upon the addition of water. 



CHAPTER XXXI. 

RENOVATED BUTTER. 

Statistics show that more than a bilhon pounds of butter 
are made on farms in this country every year. Some of 
it is consumed at home, but most of it is taken to the local 
grocer. Of this latter, the best grades usually find ready 
sale to consumers in town. Unfortunately, dairy butter 
varies so greatly in quality, and so much of it is poor, 
that vast quantities of this product are unsalable as 
butter. 

The production of farm butter is much greater during 
the summer than it is during the winter. This results in 
an overproduction during the hot summer months, when it 
is difficult to control quality, under average farm condi- 
tions. As a consequence, much of it is finally marketed 
at the renovating plant. 

Ladles. — The chief method of disposing of this farm 
butter in the past was to add color and salt if needed, and 
work it into a homogeneous product. This reworking con- 
verted the various colors and qualities of butter into one 
batch having a uniform color, degree of saltiness, and 
quality. Heavy salting was usually practiced to conceal 
the undesirable flavors. This reworked butter is known 
commercially as ladles or ladled butter. Only the best 
farm butter, of most uniform color and salt content, is 
now used for ladles. The remainder is manufactured into 

renovated or process butter. 

270 



RENOVATED BUTTER 27 1 

Origin of Renovated Butter. — The chief drawbacks to 
ladled butter was that the bad flavors were still in the 
finished product, and the body was weak. This gave 
rise, in the early eighties, to some experiments for the pur- 
pose of finding a method of eliminating the bad flavors 
from the raw product. 

Melting butter, separating out and canning the fat for 
use in tropical countries, had been practiced in some sec- 
tions of Europe for many years; but recovering the pure 
butter fat and again converting this substance into butter 
is an American invention. In 1883 butter was renovated 
by this method in Memphis, Missouri. 

In the early nineties renovated butter began to appear 
in considerable quantities on the markets of this country. 
It was commonly sold as creamery butter, usually as 
" seconds," but in time of scarcity of creamery butter 
some of the best grades would sell as " creamery extras." 
In Philadelphia it was often called " boiled " butter, and 
in Boston, " sterilized " butter. 

In 1897 the dairy and food commissioner of Pennsyl- 
vania attempted in a legal way to compel a manufacturer 
of renovated butter in Philadelphia to sell his product 
for what it was, instead of selling it as creamery butter. 
This company finally agreed to discontinue selling its 
product as creamery butter, and to print on the wrap- 
pers a name satisfactory to the commissioner. The name 
" renovated " was selected as most proper for defining 
this product. This name has been generally adopted, 
but the name " process " butter is used synonymously 
with it. 

Extent of the Industry. — In 1905, 78 factories were 
manufacturing renovated butter. Each factory has its 
own system, which the operator claims is superior to any 



272 DAIRY TECHNOLOGY 

other system; but the general process is similar in all 
cases, the differences being in the details only. 

These factories manufacture about 60,000,000 pounds 
of renovated butter per annum. 

Only the best grades of packing stock are used in this 
product; the manufacturers have learned that it is im- 
possible to make a marketable article from old rancid 
stock. Such material is of value only when used for soap- 
grease. 

The tendency to-day is toward selling cream from the 
farm; while some years ago it was largely made into butter 
which finally went to the renovating factories. The former 
method is more profitable and handier to the farmer, and 
is more in accordance with general economical principles. 

The Processes of Manufacture. 

Melting. — The butter is brought into the factory in 
barrels and dumped into the melting tank. These melt- 
ing tanks are of many different designs, one form of which 
is a tank having a coil near the bottom through which 
passes hot water. The vat is also jacketed and surrounded 
with hot water. The butter is emptied from the barrels 
into the vat, where it remains until completely melted; 
then the butter-fat oil is run out at one end through a 
strainer to remove the paper, wood and other foreign 
matter occasionally found in the raw material. As this oil 
runs from the vat and through the strainer it is pumped 
into steam-jacketed, cylindrical iron tanks, where it is 
held at a temperature of about 1 20° F. for two to three 
hours to permit the curd to settle out. This " slush," as 
the settlings are called, is drawn out through a valve at 
the bottom of the tank, and run through an old-style, 



RENOVATED BUTTER 273 

hollow-bowl, Danish- Weston separator, and the recovered 
oil added to the main batch. 

Refining the Oil. — This clear oil is run into a second set 
of tanks, or kettles, kept at a constant temperature of 
about 120° F. for several hours. During this time, pure, 
hot air is continuously pumped through the fat. The air is 
conducted to the bottom of the kettle through a pipe ex- 
tending through the oil from the top. This air rises and 
causes a constant ebullition of the oil. This aeration at a 
high temperature removes practically all the bad odors and 
flavors, and leaves an almost tasteless, clear, yellow oil. 

Making the Emulsion. — This oil is emulsified with sour 
milk, in order to reincorporate into it a natural butter 
flavor and the components of normal butter. For this 
purpose a quantity of good fresh skim milk is ripened with 
a commercial culture of lactic-acid bacteria, just as a starter 
is made in a butter or cheese factory. To this sour milk 
is added about twice its volume of sweet skim milk; then 
this mixed milk is added to the molten oil in the ratio of 
about one part milk to one and one-half parts oil. The 
milk and oil are mixed and emulsified in a cylindrical tank 
or kettle in which there is a rapidly revolving dasher. In 
some factories the emulsion is made in the same kettle 
in which the renovating process occurred. The mixing is 
accomplished by passing air through the mixture. 

Crystallizing the Fat. — This emulsion is then run into a 
large vat of water at a temperature of 36° to 46° F., which 
crystallizes the fat. Even though such a large percentage 
of milk is present it is all incorporated in the fat crystals. 
The water shows no trace of milkiness. 

The crystallizing vat is usually placed directly under- 
neath the bottom of the renovating or mixing kettle. This 
latter tapers at the bottom to a small mouth. A valve at 



274 DAIRY TECHNOLOGY 

this place enables the operator to govern the size or amount 
of fat that runs into the crystallizing tank. The water 
used in the crystallizing process is kept cold by the use of 
crushed ice or by mechanical refrigeration. 

The butter crystals are scooped from the surface of the 
water, piled on trays or trucks and run into a cooler to 
drain and ripen over night. Holding this for several hours 
at a low temperature before salting and working improves 
the body of the final product and enables the fat to absorb 
the milky flavors. 

Working and Salting. — On the following morning, the 
butter granules are put into a combined churn and worker, 
worked in brine several revolutions to work out the excess 
of buttermilk, then drained, dry-salted, worked until the 
salt is dissolved, and finally removed from the churn and 
packed into tubs, 62I pounds being weighed into each tub. 

The word " Process " or " Renovated " is imprinted in 
the butter and also marked on the outside of the tub in 
accordance with the requirements of Internal Revenue 
Department. As the flavor of the butter is better when a 
week old than when fresh it is usually kept in the refrigerator 
several days before it is shipped out. 

Extracts from United States Laws Relating to Reno- 
vated Butter. — " Manufacturers of process or renovated 
butter shall pay a special tax of $50 per year, and manu- 
facturers of adulterated butter shall pay $600 per year. 
Every person who engages in the production of process 
or renovated butter or adulterated butter as a business 
shall be considered to be a manufacturer thereof. 

That every person who carries on the business of manu- 
facturer of process or renovated butter or adulterated 
butter without having paid the special tax therefor, as 
required by law, shall, besides being liable to the payment 
of the tax, be fined not less than $1000 and not more than 



RENOVATED BUTTER 275 

$5000; and every person who carries on the business of 
a dealer in adulterated butter without having paid the 
special tax therefor, as required by law, shall, besides 
being liable to the payment of the tax, be fined not less 
than $50 nor more than $500 for each offense. 

That every manufacturer of process or renovated butter 
or adulterated butter shall file with the collector of inter- 
nal revenue of the district in which his manufactory is 
located such notices, inventories, and bonds, shall keep 
such books and render such returns of material and prod- 
ucts, shall put up signs and affix such number of his 
factory, and conduct his business under such surveillance 
of officers and agents as the Commissioner of Internal 
Revenue, with the approval of the Secretary of the Treas- 
ury, may by regulation require. But the bond required 
of such manufacturer shall be with sureties satisfactory 
to the collector of internal revenue, and in a penal sum 
of not less than $500; and the sum of said bond may be 
increased from time to time and additional sureties re- 
quired at the discretion of the collector or under instruc- 
tions of the Commissioner of Internal Revenue. 

Renovated butter having 16 per cent or more of moisture 
will be held to contain ' abnormal quantities of water, 
milk or cream,' and be, therefore, classed as ' adulterated 
butter.' 

All renovated butter may be packed by the manufac- 
turer thereof in firkins, tubs, or packages of wood or other 
suitable material not before used for that purpose; but 
each package must contain not less than 10 pounds; and, 
when packed in a solid body or mass, there shall be stamped 
or branded into the upper surface of the butter the words 
* Renovated Butter ' in one or two Unes, the letters to 
be gothic style, not less than one-half inch square and 
depressed not less than one-eighth inch. 

Manufacturers will be permitted to pack prints, bricks, 
or rolls of renovated butter not less than one pound in 
weight; but each print, brick, or roll must have stamped 
thereon the words * Renovated Butter ' in two lines, 
the letters to be depressed, of gothic style, not less than 



276 DAIRY TECHNOLOGY 

three-eighths Inch square and sunken not less than one- 
eighth inch. The contents of any package less than ten 
pounds will be considered as a brick or roll." 

Test for Renovated Butter. 

Spoon Test. — Heat about five grams of the sample to 
be tested in a large spoon over a small flame. Genuine 
butter will boil quietly, but with the production of con- 
siderable froth and foam. Renovated butter or oleo- 
margarine will sputter noisily, but will not foam much. 
The curd in the former will be small and finely divided: 
while in the latter it will be found in larger masses or lumps. 

To distinguish renovated butter from oleomargarine 
it is necessary to use the butyro-refractometer or the 
chemical tests as described under " Oleomargarine." 



CHAPTER XXXII. 

OLEOMARGARINE. 

Oleomargarine, Butterine, Dutch Butter and Mar- 
garine are terms that are used synonymously. All refer 
to articles which are manufactured as butter substitutes. 
They are all made chiefly from beef fat, and are made 
to imitate butter as nearly as possible. To some of the 
better grades (as butterine), a definite amount of real 
butter or cream is added. Beef fat is chiefly composed 
of tissue and fats belonging to the non-volatile and in- 
soluble group, such as stearin, palmatin and olein. The 
chief difference between butter and margarine is that the 
butter contains fats of the lower series which belong to 
the volatile and soluble group, of which butyrin is the 
chief one. Margarine does not contain any noticeable 
amount of the volatile fats unless butter has been added, 
as is sometimes the case. Oleomargarine is therefore not 
a dairy product, but is briefly mentioned here because dairy 
products are used in connection with its manufacture. 

Origin of Margarine. — According to history, marga- 
rine was first manufactured in France. It is said that a 
French chemist named M. Mege-Mourier was requested 
by the French Emperor, Napoleon III, to investigate the 
problem of getting a good, wholesome and cheap substi- 
tute for butter. This was evidently done to reduce the 
expenses during the France-German war of 1870. In 
a short time he had prepared a quality of goods which 
resembled butter to such an extent that it required an 

277 



278 DAIRY TECHNOLOGY 

expert to distinguish it from that product. The new 
article was named after the discoverer and the fat from 
which it was made, viz., " Margarine-Mourier." The 
new substitute for butter had many good quahties, and 
could be prepared from ox tallow in a very simple way. 

The Paris Health Counsel on April 12, 1872, admitted 
the sale of the new fat, provided it was not brought into 
the commercial market under the name of " butter." 

The Original Process. — The process which M. Mourier 
used was an excellent one. Nothing but the very best 
of fat was used. The stearin was separated from it, thus 
leaving a fat with a relatively low melting-point, similar 
in that respect to butter. The raw fat possessed a pe- 
culiar and undesirable animal taste which his particular 
process of manufacture eliminated. 

The thoroughly washed and finely chopped fat was put 
into a tank. For every 1000 parts of fat, 300 parts of 
water, i part of carbonate of potash and two well-cleaned 
stomachs of pigs or sheep were added. The mixture was 
held at a temperature of 113° F. for a few hours to digest 
the fatty tissue. It was then allowed to cool to effect the 
crystallization of the stearin and palmatin, after which it 
was put into a press. The term " oleomargarine " was 
applied to this new expressed fat. The product was pure, 
wholesome and nutritious. The manufacture of it soon 
became an established industry in France, America, Ger- 
many, Austria, Russia, Holland and other countries. It 
was an excellent cooking fat, containing a greater per- 
centage of fat, and possessing better keeping qualities 
than average butter, and excelling poor butter in flavor. 

Developments in the Industry. — The result of this ex- 
tended use of the oleomargarine was that not enough 
raw material could be secured. As a result, the ox tallow, 



OLEOMARGARINE 279 

which was formerly purified and melted at a temperature 
of 113° F,, was now exposed and melted at 140° F. This 
included more of the fats having a high melting-point, in the 
margarine oil. 

This new process overthrew the desirable Mege-Mourier 
process of manufacture of oleomargarine. According to 
his method, 100 pounds of raw material yielded only about 
twenty-two pounds of margarine, and, according to the new 
method, 100 pounds of a raw tallow yielded about sixty- 
one pounds. The latter product, however, was of an in- 
ferior quality. It was more solid and richer in stearin. 
It had a melting-point of about 110° F., which was a very 
serious objection to its healthfulness. 

In order to lower the melting-point of this substance 
and apparently to improve its usefulness, the cheaper kinds 
of vegetable oils were used, such as cottonseed oil, rape oil, 
the purer grades of olive oil, sesame oil, cocoa oil, etc. The 
increased use and consequent demand for oleomargarine 
forced the manufacturers to make use of other fats than 
ox tallow. According to patents taken out in Europe, the 
following fats were used: Bacon fat, goose fat, veal tal- 
low, stearin fat from soap manufacturers, slaughter house 
fat and fat from flaying houses. Some of the fats had a 
very undesirable smell, and were purified by treating with 
strong mineral acids. 

From this it will be seen that oleomargarine became a 
cheap adulterated food. In the face of this, the sale and 
manufacture of it continued to increase and became very 
extensive. Especially was this so in the United States, 
where in the large cities, at the big slaughtering houses, 
so much animal fat accumulated. 

Manufacture of Oleomargarine. — It is impossible to 
describe in a precise detailed form each specific operation 



28o DAIRY TECHNOLOGY 

which the raw material for oleomargarine must undergo, 
because the processes of manufacture, especially in the 
United States, are considered to be trade secrets. 

The caul fat of freshly killed beeves is, after a thorough 
washing, first in tepid water, then in ice water, allowed to 
stand in a cold room until thoroughly chilled. It is then 
rendered between a temperature of 130° and 175° F. The 
resulting oil is allowed to cool slowly until a considerable 
portion of the stearin and palmitin has crystallized out. 
This pasty mass is then subjected to hydraulic pressure. 
The oil or fluid part (about two-thirds of the whole) flows 
out into a tank of cold water, where it solidifies into a 
granulated mass known to the trade as " oleo " oil, or 
simply " oleo." The name " oil " is somewhat misleading, 
as the product is a granular sofid of a dull whitish color. 
Fresh leaf fat treated in exactly the same way as the beef 
tallow yields the " neutral " lard or " neutral " of the trade, 
also a granular solid of a white color. 

The objects of this treatment are twofold: to produce 
fats as free as possible from taste and odor; and to remove 
some of the stearin and palmitin, in order that the finished 
product may have a lower melting-point. 

The " oleo " and the " neutral " are then mixed. The 
proportions vary according to the marketing place of the 
product (a warm climate calling for more "oleo," a cold 
one for more " neutral ") and the amount of butter with 
which the mixture is flavored. This mixing is done in 
large, steam-jacketed vessels provided with revolving 
paddles, by which their contents can be easily mixed. 
Here the " oleo " and the '' neutral " are thoroughly 
agitated with a certain proportion of milk (soured by in- 
oculation with a pure culture of lactic-acid bacteria), 
and sometimes with cream, butter and cottonseed oil, 



OLEOMARGARINE 281 

depending upon the grades of the product to be manu- 
factured. 

Having been brought into a perfect emulsion, the mixture 
is run into a vat of ice water, which causes the formation 
of crystals or granules of fat similar to small granules of 
butter, such as are formed in the churning of cream. 

The fat granules are held at a low temperature several 
hours to ripen, then put into a churn, worked and salted 
just as in the manufacture of renovated butter. 

The proportions in which these raw materials are mixed 
are given by the 12th Census Report of the United States 
for each of the three high grades of oleomargarine manu- 
factured as follows: High grade, 

pounds. 

Oleo oil 100 

Neutral lard 130 

Butter 95 

Salt 32 

Color 00.5 

357-5 
will produce about 352 pounds of oleomargarine. 

Medium high grade, 
pounds. 

Oleo oil 315 

Neutral lard 500 

Cream 280 

Milk 280 

Salt 120 

Color 1-5 

1496 -5 
will produce from 1050 to 1080 pounds of oleomargarine. 

Cheap grade, 
pounds. 

Oleo oil 495 

Neutral lard 265 

Cottonseed oil 315 

Milk 25s 

Salt 120 

Color 1.25 

1451- -'5 
will produce from 1265 to 1300 pounds of oleomargarine. 



282 



DAIRY TECHNOLOGY 



The following formulas are taken from " The Modern 
Packing House," by F. W. Wilder, former general super- 
intendent of Swift & Co., and Schwarschild & Suls- 
berger : 

" Neutral or No. i. oleo oil is made from the following: 

Gaul fat, ruffle fat, gaul piece of gut end, briskets 

trimmed from the bed pickings, crotch trimming from the 

bed pickings, paunch trimmings, pluck trimmings, reed 

trimmings, heart casing fats. 

No. 3 or third grade oil: 

Head fat, fat trimmed from cattle heads when checking, 
plucking sweet-bread trimming, liver trimmings, bladder 
trimmings, fat from chilled beef tongues when they are 
trimmed, miscellaneous fats from other departments which 
are kept clean, the first washings from the oleo press cloths 
before soda has been used, scrap vat skimmings from the 
second grade oil." 

The following formulas are for making butterine or 
oleomargarine of three different grades: 

FORMULA FOR AND COST OF HIGH GRADE 
OLEOMARGARINE. 



Material and Quantities. 




Total cost. 



526 lbs. No. I oleo oil. . . . 
476 lbs. No. I neutral oil. 
50 gals. 30 per cent cream 
300 lbs. creamery butter. 

Labor and package 

Salt and color 

Total 



5214.00 



This formula will yield 1500 pounds of butterine. There- 
fore the cost is $0.1426 per pound. 



OLEOMARGARINE 

FORMULA FOR AND COST OF MEDIUM GRADE 
OLEOMARGARINE. 



283 



Material and quantities. 


Cost per 
pound. 


Total cost. 


525 lbs. No. I oleo oil 


$0.0875 
0.08125 
0.42 
O.OI 
0.00 


$45-93 

38.60 

40.32 

12.00 

I 00 


475 lbs. No. I neutral lard 


40 gals. 30 per cent cream 

Labor and package 

Salt and color 






Total 




$137-80 



This formula will yield 1200 pounds of oleomargarine. 
Therefore the cost is $0.1142 per pound. 



FORMULA FOR AND COST OF LOW GRADE 
OLEOMARGARINE. 



Material and quantities. 


Cost per 
pound. 


Total cost. 


350 lbs. No. 2 oleo oil . 


$0.08 
0.04 
0.08125 
0. 12 


$28 00 


250 lbs. cottonseed oil 


10 00 


450 lbs. neutral lard 


36.54 
7.20 

12.00 
1 .00 


60 gals. 25 per cent milk 

Labor and package 

Salt and color 


Total 




$94 • 74 



This formula will yield 1200 pounds of oleomargarine. 
Therefore the cost of producing and packing for shipment 
will be $0.0789 per pound. 

From the above it will be seen that the extra prime, 
yellow cottonseed oil, known as butter oil, is not used in 
the best grades of oleomargarine. This agrees with what 
Mr. Jelke, a manufacturer of oleomargarine, stated be- 
fore the agricultural committee, that they did not use 
cottonseed oil in their best grades of oleomargarine, as 
it injured the flavor. Consequently, he stated that the 



284 DAIRY TECHNOLOGY 

best grades of oleomargarine were white or light in 
color. 

Quantity of oleomargarine produced/ 1888 to 191 1 
inclusive : 

Pounds of 

'^saT. Oleomargarine. 

1899 83,130,474 

1900 107,045,028 

1901 104,943,856 

1902 126,316,427 

1903 73,284,096* 

1904 50,199,642 

1905 51,987,336 

1906 554,34,900 

1907 71,366,77s 

1908 81,525,600 

1909 92,282,815 

19IO 141,862,280 

1911 121,162,79s 

Total, pounds 739. 106, 239 



For two years, from 1902, the production of oleomar- 
garine decreased. This, no doubt, is attributable to the 
act of May 9, 1902, which went into effect July i of that 
year. 

(Annual Report, Commissioner of Internal Revenue, 
1911): 

A great deal of oleo oil is manufactured in this country 
and exported to Europe. It is said that in Holland there 
are 70 factories which get their oleo oil largely from the 
United States. 

Food Value. — Oleomargarine, when made in compli- 
ance with the laws of the land, is a legally recognized prod- 

1 Bureau of Statistics, U. S. Dept of Agr. 

* First year new Oleo Law, imposing lo-cent tax on colored margarine, 
was in force. 



OLEOMARGARINE 285 

uct which has its place on the market. The lower grades 
are used in place of cooking butter and the higher grades 
(composed partly of butter) as a substitute for table butter. 

There is some difference of opinion among authorities 
as to the healthfulness of oleomargarine as compared 
with butter. We quote two authorities as follows: 

In record No. 7 from United States Department of Agri- 
culture H. Lubrig discusses the relative digestibility of 
oleomargarine and natural butter. The author reviews 
the literature on the subject and reports results of four 
experiments on the digestibility of oleomargarine and 
butter, made with a healthy man 29 years old and weigh- 
ing 175 pounds. Holstein butter and three sorts or grades 
of oleomargarine were used, named according to their 
quahties — -Nos. i, 2 and 3. The tests were similar, the 
fat in each case forming part of a mixed diet of meat, 
bread, vegetables, etc. In the author's opinion the true 
undigested fat was not oleomargarine or butter fat, and 
accordingly he believes it is safe to conclude that butter 
and oleomargarine are completely digested. From a 
physiological standpoint the two fats are thought to be 
completely digestible and of equal value. 

On the other hand H. W. Wiley, former chief chemist 
of the Department of Agriculture at Washington, who 
testified before the House Agricultural Committee when 
the Grout bill was being considered, said: '' This is exactly 
what I said in my testimony before the senate committee. 
They asked me if I thought oleomargarine was as digestible 
as butter. I do not think it is. I do not think it digests 
so well as butter, because it contains more of the higher 
series of fatty acids, and practically none of the lower 
acids which are more easily decomposed under the influence 
of ferments. All digestion is fermentation." 



286 DAIRY TECHNOLOGY 

Oleomargarine Law. — Congress passed a law which 
became effective July i, 1902. The principal features of 
this law are as follows: Tax on colored oleo is increased 
from 2 to 10 cents per pound. Tax on uncolored oleo 
is reduced from 2 to j cent a pound. Wholesale and re- 
tail dealer's license for the sale of colored oleo was not 
changed, but remained $480.00 and $48.00 per year re- 
spectively. Wholesale dealer's Hcense for the sale of un- 
colored oleo was reduced from $480.00 to $200.00 per 
year. Retail dealer's license for the sale of uncolored oleo 
was reduced from $48.00 to $6.00 per year. A license 
costing $480.00 entitled the holder to wholesell either 
colored or uncolored or both; and a license costing $48.00 
entitled the holder to retail colored, or uncolored or both. 

Hotels, restaurants, boarding-houses, railroad contrac- 
tors, and soldiers' homes, schools and other public institu- 
tions are prohibited from buying the uncolored oleo and 
coloring it. A family (not keeping boarders) is permitted 
to buy the uncolored article and color it. 

Since the passage of this law, the manufacturers have 
learned to use fats that will give their product a yellow 
color without the addition of any artificial coloring matter. 
This is done by using fat from pasture-fed animals and June 
butter having a natural high color. 

However, many of the States have enacted laws pro- 
hibiting the sale of yellow oleomargarine, regardless of 
whether the color be artificial or natural. Another pro- 
vision adopted by several States is that when a substitute 
for butter is used for cooking or served as a food in hotels, 
restaurants, etc., a placard shall be placed opposite each 
table or counter, which placard shall have the words 
" Substitute for butter used here " printed in large, legible 
type. 



OLEOMARGARINE 287 

Detection of Oleomargarine. — The spoon test: This 
test is described in the chapter on " Renovated Butter." 

Waterhouse test: Add about 5 grams of the sample to 
be tested to 50 cubic centimeters of hot skim milk, cool 
slowly, and stir with a small wooden stick while cooHng. 
In solidifying, the fat, if oleomargarine, will mass into a 
lump or clot; but if butter, it will not, but will remain 
in small particles distributed throughout the milk. 

Chemical tests: In the chemical laboratory oleomar- 
garine may be distinguished from butter by determining 
the amount of volatile and soluble acids in each. 

The Reichert-Meisel number (number of cubic centi- 
meters N/io alkali required to neutralize the volatile 
acids in 5 grams of fat) is the most rehable indication of the 
kind of fat. The Reichert-Meisel number for butter may 
vary from 25 to 32 ; for oleomargarine, from .5 to 10, depend- 
ing upon the percentage of butter used in the process of 
manufacture. 

In butter fat the soluble acids constitute from 3 to 6 per 
cent of the whole: in oleomargarine, from .1 to 1.5. 

Butyro-refractometer reading: Owing to the difference 
in the refractive indices of various fats and oils, butter 
may be distinguished from oleomargarine by means of 
the butyro-refractometer. This is a very simple method, 
requires but little time, and, with few exceptions, is re- 
liable. The refractometer reading of butter is normally 
50 to 54 at 25° C. Higher readings indicate the presence 
of oleo oil. According to Wollny, samples having a reading 
higher than 54 will, upon chemical analysis, be found to 
be adulterated. Pure oleomargarine will show a reading 
of 58 to 66. 



I NDEX 

A. 

PAGE 

Acidity of cream for ice-cream 139 

test for sanitary milk 123 

Adhesiveness of milk 2 

Advantages of ice-cream makino; in local creamery 174 

score-card inspection of farms and milk 41 

Aufaits 137 

B. 

Babcock method for testing ice-cream 188 

Bacteria in raw and pasteuiized milk 103 

ice-cream 189 

Batch ice-cream freezing machine 167 

Binders and fillers for ice-cream ; . 146, 186 

Bisque ice-cream 137 

Bitter milk 24 

Bottle pasteurizer loi 

Bottling milk 104 

Bottles, washing of 105 

kinds of 109 

kinds of caps for no 

Brick ice-cream 135 

Brine, system of refrigeration 196 

properties of calcium chloride and sodium chloride 197 

Butter as a food 19 

composition of 20 

from whey 211 

fuel value of butter fat 83 

renovated 270 

Buttermilk as a food 17, 234 

artificial 235 

bacillus bulgaricus for 236 

composition of 18, 234 

cream from 210 

for cheese 207 

289 



290 INDEX 

PAGE 

Buttermilk as a food, tablets and capsules 233, 237 

use as poultry food 231 

By-products of creameries and cheeseries 203 



C. 

Calcium chloride brine, properties of 197 

Can washer for ice-cream cans 171 

Cans, ice-cream packing 171 

Caps for milk bottles no 

Carbohydrates, fuel value of 83 

Carbonated milk 247 

Casein, manufacture of 221 

from buttermilk 224 

products from 225 

foodstuffs from 230 

Certified milk 5°, 55 

amount produced 56 

commissions supervising 64 

cost of inspecting 63 

definition of 56 

origin of 55 

production of 65 

recjuirements of, in New York 57 

use and advantages of 64 

Cheddar cheese, food \'alue of 20 

City milk plant 88, 94 

Clarifying milk 97 

Classification of ice-cream 135 

Classification of nutrients in milk 5 

Colored milk 24 

Colostrum milk, cows' 24 

Composition of cows' milk 3 

kefir 240 

condensed and evaporated milk 261, 262 

kumiss 241 

milk powder 269 

different kinds of skim milk 16 

buttermilk 18, 234 

Cheddar cheese 21 

milk sugar 216 

colostrum milk 24 

cottage cheese 22 



INDEX 291 



PACE 



Composition of human milk and cows' milk 81 

cream 19 

whey 211 

Condensed milk 249 

extent of industry 249 

U. S. standards for 250 

processes and factors governing manufacture of 253 

composition of 261,262 

quality of raw products for 251 

Cones for ice-cream making 170 

Contests, milk and cream 45 

Continuous ice-cream freezing machine 167 

Cooling milk and cream 141 

Cost of pasteurizing milk 73 

inspecting milk 36 

milk, compared with other foods 10 

Cottage cheese, food value of 21 

manufacture of 203 

preparing milk for 204 

separating curd from whey 205 

use of rennet, hydrochloric acid, and lactic acid in 

making 206 

use of buttermilk for 207 

yield of 205 

Cows, number of dairy, in U. S 28 

Cream for ice-cream 139 

acidity of 140 

fat contents of 141 

importance of cooling 141 

homogenizing of 140 

pasteurization of 140 

Cream, Moscow sour 245 

Devonshire or clotted 246 

D. 

Devonshire cream, preparation of 246 

Digestibility of milk 8, 10 

Diseases affecting milk 26 

E. 

EpideiTiics spread by milk 32 

Equipment of village milk plant 87 

small ice-cream factory 175 



292 INDEX 

. F. 

PAGE 

Factories, ice-cream, local creameries 173 

advantages and disadvantages of 174 

cost of equipping 175 

ecjuipment of large city 176 

Fancy ice-cream 135 

how to make 158 

Fat content of different parts of ice-cream 159 

Fat, per cent in cream for ice-cream 141, 186 

testing ice-cream for 188 

Fermented milk, kinds, uses, and value of 232 

Fillers and binders for ice-cream 146, 186 

Flavor of ice-cream, factors governing 143 

amount to use for ice-cream 144 

Food value, of milk, skim milk, buttermilk, cream, butter, cheese, cot- 
tage-cheese 1,21 

needed by people of various ages 17 

requirements of infants 82 

Frappes 137 

Freezing machines 165 

Freezing point of cieam 154 

effect of sugar on 155 

Freezing ice-cream, salt and ice to use in 150 

speed of dasher a factor in 153 

length of freezing period 153 

Fruit ice-cream 136, 161 



G. 

Gallalith, manufacture and use of 228 

Gelatin for filler in ice-cream 148 

Glue- from casein 225 



H. 

Hardening of ice-cream ^57, 179 

History of ice-cream manufacture 132 

Homogenized milk 84 

Homogenization for ice-cream . 140 

Homogenizing machine for ice-cream 169 

Human milk vs. cows' milk 81 



INDEX 293 
I. 

PACE 

Ice breaker and ice crusher 168 

Ice-cream, time of freezing 153 

freezing point of 154 

factors governing "swell" 155 

when to stop freezing and hardening 157 

how to handle returned goods 157 

fancy, how to make 158 

processes of manufacture in large plants 176 

fat content of different portions 159 

formulas for different kinds 160 

freezing machines for 165 

profits from 1 75 

macliinery for making 163 

use of homogenizcr for 169 

history of ^. 132 

freezing of 150 

classification of 135, 136 

flavors and sugar to use 144 

fillers and binders 147, 186 

flavor of, factors governing 143 

score card for 182 

per cent fat, standard for 186 

standardization of cream for 180 

testing for fat in 188 

bacteria in 189 

freezing by use of brine 196 

Ices, water ice, sherbet, sorbet, granites, punches 136, 143 

Improvement of milk supply 51 

Infant mortality, relation to milk supply 30 

relation to pasteurized milk 75 

Infants', food rccjuirements of 82 

Infants' milk depots in New York and other cities 52, 53 

formula for modifying milk at 54 

Inspected milk 66 

Inspection of farms and rnilk supply 35 

advantages of 41 

cost of 36 

of city milk plants 43 

Inspections, numl:)er made in New York 47 

limitations of 47 

results of 42 



294 INDEX 

PAGE 

Inspections, use of score card 37 

Insulation of refrigerated rooms 201 

K. 

Kefir, preparation of 238 

composition of 240 

Kumiss 241 

composition of 242 

L. 

Lacto, formula for 137, 161 

Ladles 270 

Laws and ordinances pertaining to pasteurized milk 78 

governing manufacture and sale of oleomargarine 286 

regulating manufacture and sale of renovated butter 274 

Leucocytes in milk 125 

M. 

Milk, definition of i 

abnormal, poisonous, colored, bitter, etc 23 

bacteria in raw vs. pasteurized 76 

modified, digestibility of 80 

certified, production and use of 55 

inspected, production and use of 67 

chief nutrients in 4 

composition of cows', various breeds 3 

variation in composition of 3 

and its products as foods 4 

curdling of 2 

reaction of 2 

purpose of i 

properties of i 

nutritive ratio of 5 

palatability and digestibility of 7,8 

raw vs. heated 9 

relative cost of 10, 13 

food value of skim 14 

diseases of. affecting sanitation 25, 32 

per capita consumption in various cities 27 

supply of New York city for twenty-five years 28 

sources and conditions of city supply 2g 

investigation of. in Illinois 29 

relation of, to infant mortality 30 



INDEX 295 

PACE 

Milk, contamination of ^' 

cost of inspecting ■^ 

inspection of city 43 

and cream contests 45 

classes of, in New York ^S 

inspected -' 

modified '^ 

results of improving ^ 

depots in New York 5 ^ 

pasteurized, advantage of 7 

home pasteurized '^ 

human, composition of colostrum, nomial 81 

manner of modifying •S 



homogenized. 



84 



cooling and bottling in small plant 89 

transportation of, to plant 94 

clarifying 97 

bottling of, in city milk plant 245 

carbonated '^' 

leucocytes in ^ 

condensed "49 

delivering ' -^ 

fermented 

kinds of bottles for ^°9 

standardizing, manner and importance ^H 

sanitary examination of ^ -•5 

24s 

ropy ^^ 

sugar, history and manufacture of 2^° 

manufacture of, in United States 217 

by-products of manufacture of 219 

composition of ^^ 

, 264 

powder 

advantages, history and development of 264 

modern method of manufacture 267 

composition of " 9 

r .... 268 

uses 01 

Mix, freezing of ice-cream ^^ 

Modified milk, use and digestibility of ^° 

Modifying milk, manner of ^ 

Moscow sour cream, preparation of ^4.i 

I ^7 

Mousse ■; 

formula for 

Mysost, manufacture of ^ 



296 INDEX 



N. 

Neapolitan ice-cream 135 

Neutralization of cream 139 

Nutrients in milk 5 

in one pound of various food products 12 

cost of, in different food products 13 

Nutritive ratio of milk 6 

Nut ice-cream 136 

O. 

Oleomargarine, history, origin, and development of 277 

manufacture of 279 

formulas for 281 

yield of 283 

amount sold 284 

food value of 284 

U. S. laws pertaining to sale of 286 

detection and tests for 287 

Ordinance pertaining to pasteurization 178 

Overrun or swell of ice-cream 155 



P. 

Paint from casein 226 

Palatability of milk 7 

Parfaits 137 

formula for 161 

Pasteurized milk 50 

alleged disadvantages of 68 

changes of, chemical and bacteriological 69 

cost of 73 

advantages of 75 

relation to bacterial content 75 

increase of 77 

Pasteurizing and cooling milk in city plant 98 

Pasteurizers, kind of 100 

Pasteurizer for ice-cream 140 

Pasteurization of milk, supervision of 77 

laws and ordinances pertaining to 78 

home 79 



INDEX 297 

PAGE 

Philadelphia ice-cream ^■^^ 

Plain ice-cream 

Poisonous milk 

Powder milk 

whey " " 

Properties of milk 

Proteids, fuel value of ^ 



R. 

Raw vs. heated milk 9 

Reaction of milk 

Reduction-fermentation test ^ - ' 

Refrigeration, mechanical ^"^-^ 

principles of ^94 

size of compressor and strength of brine i97 

operation of plant ^9° 

Renovated butter ~''° 

origin and extent of -7^ 

processes of manufacture 272 

U. S. laws regulating sale of 274 

test for 276 

Ropy milk -4-245 



S. 

Sanitary pipes and fittings ^'i 

Score card for farm and milk inspection 37 

advantages and results of using 4^ 

for market milk 45 

for ice-cream ^°- 

Sediment test for millc ^ --^ 

Sherbet, formula for ^"- 

Skim milk, value of different kinds ^4 

composition of ^■^ 

Sodium chloride brine, properties of ^97 

Souffles ^-57 

Speed of ice-cream dasher ^^3 

Specific gravity of milk - 

heat of milk ^ 

Standardized milk and cream 114, HQ, i^o 

formulas for standardizing i^3. 18° 

Swell of ice-cream, factors governing ^55 



298 INDEX 

T. 

PAGE 

Tests for sanitary milk 123 

reduction fermentation 126 

acidity 123 

sediment 124 

Toxins in milk 72 

Tragacanth, gelatin, and Indian gum for ice-cream fillers 148 

Tuberculosis, relation of, to milk supply ss 

V. 

Vanilla ice-cream, formula for 160 

Variation in composition of cows' milk 3 

Viscogen for cream 128 

Viscosity of milk 2 

cream, preparing viscogen 127 

W. 

Whey, composition of 211 

Whey butter 211 

methods of manufacture 211 

profits from 215 

markets for 214 

powder 269 

Whitewash paint from milk 226 

Y. 

Yoghurt 244 



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Merriman and Brooks — Handbook for Surveyors 16mo, mor. 

Nugent — Plane Surveying Svo 

Ogden — Sewer Construction Svo 

Sewer Design 12mo 

Ogden and Cleveland — Practical Methods of Sewage Disposal for Resi- 
dences, Hotels, and Institutions Svo 

Parsons — Disposal of Municipal Refuse Svo 

Patton — Treatise on Civil Engineering Svo, half leather. 

Reed — Topographical Drawing and Sketching 4to 

RiEMER — Shaft-sinking under Difficult Conditions. (Corning and Peele.) 

Svo 

Siebert and Biggin — Modern Stone-cutting and Masonry Svo 

Smith — Manual of Topographical Drawing. (McMillan.) Svo 

Soper — Air and Ventilation of Subways 12mo 

Tracy — Exercises in Surveying 12mo, mor. 

Plane Surveying 16mo, mor 

Ven.able — Garbage Crematories in America Svo 

Methods and Devices for Bacterial Treatment of Sewage Svo 

Wait — Engineering and Architectural Jurisprudence Svo 

Sheep 

Law of Contracts Svo 

Law of Operations Preliminary to Construction in Engineering and 

Architecture Svo 

Sheep 

Warren — Stereotomy — Problems in Stone-cutting Svo 

Waterbury — Vest-Pocket Hand-book of Mathematics for Engineers. 

2s X5| inches, mor. 

Enlarged Edition, Including Tables mor. 

Webb — Problems in the Use and Adjustment of Engineering Instruments, 

16mo, mor. 
Wilson — Topographic, Trigonometric and Geodetic Surveying Svo 

6 



BRIDGES AND ROOFS. 

Bishop — Structural Details of Hip and Valley Rafters... Oblong large 8vo. *$1 75 
BoLLER — Practical Treatise on the Construction of Iron Highway Bridges 

8vo, 2 00 

Thames River Bridge Oblong paper, *5 00 

Burr and Falk — Design and Construction of Metallic Bridges 8vo, 5 00 

Influence Lines for Bridge and Roof Comp-atations 8vo, 3 00 

Du Bois — Mechanics of Engineering. Vol. II Small 4to. 10 00 

Foster — Treatise on Wooden Trestle Bridges 4to, "5 00 

Fowler — Ordinary Foundations 8vo, 3 50 

Greene — Arches in Wood, Iron, and Stone 8vo, 2 50 

Bridge Trusses 8vo, 2 50 

Roof Trusses 8vo, 1 25 

Grimm — Secondary Stresses in Bridge Trusses 8vo, 2 50 

Heller — Stresses in Structures and the Accompanying Deformations. .8vo, 3 00 

Howe — Design of Simple Roof-trusses in Wood and Steel 8vo, 2 00 

Symmetrical Masonry Arches 8vo, 2 50 

Treatise on Arches 8vo, 4 00 

Hudson — Deflections and Statically Indeterminate Stresses Small 4to, *3 .50 

Plate Girder Design 8vo, *1 50 

Jacoby — Structural Details, or Elements of Design in Heavy Framing, 8vo, *2 25 
Johnson, Bryan and Turneaure — Theory and Practice in the Designing of 
Modern Framed Structures. New Edition. 

Part I. Stresses in Simple Structures 8vo, *3 00 

Part II. Statically Indeterminate Structures and Secondary Stresses 

8vo, *4 00 
Merriman and Jacoby — Text-book on Roofs and Bridges: 

Part I. Stresses in Simple Trusses 8vo, 2 50 

Part II. Graphic Statics 8vo, 2 .50 

Part III. Bridge Design 8vo, 2 50 

Part IV. Higher Structures 8vo, 2 .50 

RiCKER — Design and Construction of Roofs 8vo, 5 00 

Sondericker — Graphic Statics, with Applications to Trusses, Beams, and 

Arches 8vo, *2 00 

Waddell — De Pontibus, Pocket-book for Bridge Engineers. . . . 16mo. mor., 2 00 
Specifications for Steel Bridges 12mo, *0 50 

HYDRAULICS. 

Barnes — Ice Formation 8vo, 3 00 

Bazin — E.xperiments upon the Contraction of the Liquid Vein Issuing from 

an Orifice. (Trautwine.) 8vo, 2 00 

BovEY — Treatise on Hydraulics 8vo, 5 00 

Church — Diagrams of Mean Velocity of Water in Open Channels. 

Oblong 4to, paper, 1 50 

Hydraulic Motors 8vo, 2 00 

Mechanics of Fluids (Being Part IV of Mechanics of Engineering) . .8vo, 3 00 

Coffin — Graphical Solution of Hydraulic Problems 16mo. mor., 2 50 

Flather — Dynamometers, and the Measurement of Power 12mo, 3 00 

Folwell — Water-supply Engineering 8vo, 4 00 

Frizell — Water-nower 8vo, 5 00 

Fuertes — Water and Public Health 12mo, 1 50 

Fuller — Domestic Water Supplies for the Farm Svo. *1 50 

Ganguillet and Kutter — General Formula for the Uniform Flow of Water 

in Rivers and Other Channels. (Hering and Trautwine.).. .8vo, 4 00 

Hazen — Clean Water and How to Get It Small 8vo, 1 50 

Filtration of Public Water-supplies Svo, 3 00 

Hazelhurst — Towers and Tanks for Water-works 8vo, 2 50 

Herschel — 115 Experiments on the Carrying Capacity of Large, Riveted, 

Metal Conduits Svo, 2 00 

HoYT and Grover — River Discharge Svo, 2 00 

Hubbard and Kiersted — Water-works Management and Maintenance, Svo, 4 00 
Lyndon — Development and Electrical Distribution of Water Power.. Svo, *3 00 
Mason — Water-supply. (Considered Principally from a Sanitary Stand- 
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Merriman — Elements of Hydraulics 12mo, *1 00 

Treatise on Hydraulics. 9th Edition, Rewritten Svo, *4 00 

7 



MoLiTOR — Hydraulics of Rivers, Weirs and Sluices 8vo,*S2 00 

Morrison and Brodie — High Masonry Dam Design 8vo. *1 50 

Schuyler — Reservoirs for Irrigation, Water-power, and Domestic Water 

supply. Second Edition, Revised and Enlarged Large 8vo, 6 00 

Thomas and Watt — Improvement of Rivers 4to, *6 GO 

Turneaure and Russell — Public Water-supplies 8vo, 5 00 

Wegmann — Design and Construction of Dams. 6th Ed., enlarged 4to, *6 00 

Water Supply of the City of New York from 1658 to 1895 4to, 10 00 

Whipple — Value of Pure Water Small 8vo, 1 00 

WiliTiams and Hazen — Hydraulic Tables Svo, 1 50 

Wilson — Irrigation Engineering Svo, 4 GO 

Wood — Turbines Svo, 2 50 

MATERIALS OF ENGINEERING. 

Baker — Roads and Pavements Svo, 5 00 

Treatise on Masonry Construction 8vo, 5 00 

Black — United States Public Works Oblong 4to, 5 00 

Bl.\nch.\rd — Bituminous Surfaces and Bituminous Pavements. (/w Preparation.) 

and Drowne — Highway Engineering, as Presented at the Second 

International Road Congress, Brussels, 1910 Svo, *2 00 

Text-book on Highway Engineering (In Press.) 

Bottler — German and American Varnish Making; (Sabin.) . . . Small Svo, *3 50 

Burr — Elasticity and Resistance of the Materials of Engineering Svo, 7 50 

Byrne — Highway Construction Svo, 5 00 

Inspection of the Materials and Workmanship Employed in Construction. ' 

16mo, .3 00 
Church — Mechanics of Engineering Svo, 6 00 

Mechanics of Solids (Being Parts I, II, III of Mechanics of Engineer- 
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Mechanics of Fluids (Being Part IV of Mechanics of Engineering) . Svo, 3 00 
Du Bois — Mechanics of Engineering: i 

Vol. I. Kinematics, Statics. Kinetics Small 4to, 7^50 

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Theory of Flexures Small 4to, 10 00 

Eckel — Building Stones and Clays Svo, *3 00 

Cements. Limes, and Plasters Svo, *6 00 

Fowler — Ordinary Foundations ' Svo, 3 50 

Fuller and Johnston — Applied Mechanics: 

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Greene — Structural Mechanics Svo, *2 50 

Holley — Analysis of Paint and Varnish Products Small Svo, *2 50 

Lead and Zinc Pigments Small Svo, 

Hubbard — Dust Preventives and Road Binders Svo, 

Johnson (J. B.) — Materials of Construction Large Svo, 

Keep — Cast Iron Svo, 

King — Elements of the Mechanics of Materials and of Power of Transmis- 
sion Svo, *2 50 

Lanza — Applied Mechanics Svo, 

Lowe — Paints for Steel Structures 12mo, 

Maire — Modern Pigments and their Vehicles 12mo, 

M aurer — Technical Mechanics Svo, 

Merrill — Stones for Building and Decoration ; Svo, 

Merriman — Mechanics of Materials ■ Svo, 

Strength of Materials 12mo, *1 00 

Metcalf — Steel. A Manual for Steel-users 12mo, 2 00 

Morrison — Highway Engineering Svo, 2 50 

MuRDOCK — Strength of Materials 12mo, *2 00 

P.\TTON — Practical Treatise on Foundations Svo, 

Rice — Concrete Block Manufacture Svo, 

Richardson — Modern Asphalt Pavement Svo, 

Richey — Building Foreman's Pocket Book and Ready Reference. 16mo.mor., 

Cement Workers' and Plasterers' Edition (Building Mechanics' Ready 

Reference Series) 16mo. mor.. 

Handbook for Superintendents of Construction 16mo, mor.. 

Stone and Brick Masons' Edition (Building Mechanics' Ready Reference 
Series) 16mo, mor., 

s 



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RiES — Building Stones and Clay Products 8vo,*S3 00 

Clays: Their Occurrence, Properties, and Uses 8vo, *5 00 

and Leighton — History of the Clay-working Industry of the United 

States 8vo, *2 50 

Sabin — Industrial and Artistic Technology of Paint and Varnish 8vo, 3 00 

Smith — Strength of Material 12mo, *1 25 

Snow — Principal Species of Wood Svo, 3 50 

Spalding — Hydraulic Cement 12mo, 2 00 

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Taylor and Thompson — Concrete Costs Small 8vo, *5 00 

Extracts on Reinforced Concrete Design Svo, *2 00 

Treatise on Concrete, Plain and Reinforced Svo, 5 00 

Thurston — Materials of Engineering. In Three Parts Svo, S 00 

Part I. Non-metallic Materials of Engineering and Metallurgy. . .Svo, 2 00 

Part II. Iron and Steel Svo. 3 50 

Part III. A Treatise on Brasses, Bronzes, and Other Alloys and their 

Constituents Svo, 2 50 

TiLLSON — -Street Pavements and Paving Materials Svo, *4 00 

TuRNEAURE and Maurer — Principles of Reinforced Concrete Construction. 

Svo, 3 50 

Waterbury — Cement Laboratory Manual 12mo, 1 00 

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Wood (De V.) Treatise on the Resistance of Materials, and an Appendix on 

the Preservation of Timber Svo, 2 00 

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Steel Svo, 4 00 

RAILWAY ENGINEERING. 

Berg — Buildings and Structures of American Railroads 4to, 5 00 

Brooks — Handbook of Street Railroad Location 16mo, mor., 1 50 

Burt — Railway Station Service 12mo, *2 00 

Butts — Civil Engineer's Field-book 16mo, mor., 2 50 

Crand.\ll — Railway and Other Earthwork Tables Svo, 1 50 

and B.\rnes — Railroad Surveying 16mo, mor., 2 00 

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Dredge — History of the Pennsylvania Railroad. (1879) Paper, 5 00 

Fish — Earthwork Haul and Overhaul . . ; (In Press.) 

Fisher — Table of Cubic Yards Cardboard, 25 

Gilbert, Wightman and Saunders — Subways and Tunnels of New York. 

Svo, *4 00 

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Hudson — Tables for Calculating the Cubic Contents of Excavations and 

Embankments Svo, 1 00 

Ives and Hilts — Problems in Surveying, Railroad Surveying and Geodesy. 

16mo, mor., 1 .50 

MoLiTOR and Beard — Manual for Resident Engineers 16mo, 1 00 

Nagle — Field Manual for Railroad Engineers 16mo, mor., 3 00 

Orrock — Railroad Structures and Estimates Svo, *3 00 

Philbrick — Field Manual for Engineers 16mo, mor., 3 00 

R.WMOND — Elements of Railroad Engineering Svo, 3 50 

Railroad Engineer's Field Book • (In Preparation.) 

Railroad Field Geometry IGmo, mor., 2 00 

Roberts — Track Formulse and Tables 16mo, mor., 3 00 

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Railroad Spiral 1 16mo, mor., 1 50 

Taylor — Prismoidal Formulae and Earthwork Svo, 1 50 

Webb — Economics of Railroad Construction Small Svo, 2 50 

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Wellington — Economic Theory of the Location of Railways.. . .Small Svo, 5 00 

WiLSO.N — Elements of Railroad-Track and Construction 12mo, 2 00 



DRAWING. 



Barr and Wood — Kinematics of Machinery Svo 

Bartlett — Mechanical Drawing. Third Edition Svo 

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and Johnson — Engineering Descriptive Geometry Svo 

Bishop — Structural Details of Hip and Valley Rafters. . . .Oblong large Svo 

Blessing and Darling — Descriptive Geometry Svo 

Elements of Drawing Svo 

CooLiDGE — Manual of Drawing Svo, paper 

and Freeman — Elements of General Drafting for Mechanical Engineers 

Oblong 4to 

Durley — -Kinematics of Machines Svo 

Emch — Introduction to Projective Geometry and its Application Svo 

French and Ives — Stereotomy Svo 

Hill — Text-book on Shades and Shadows, and Perspective Svo 

Jamison — Advanced Mechanical Drawing Svo 

Elements of Mechanical Drawing Svo 

Jones — Machine Design: 

Part I. Kinematics of Machinery Svo 

Part II. Form, Strength, and Proportions of Parts Svo 

Kimball and Barr — Machine Design Svo 

MacCord — Elements of Descriptive Geometry Svo 

Kinematics; or. Practical Mechanism Svo 

Mechanical Drawing 4to 

Velocity Diagrams Svo 

McLeod — Descriptive Geometry Small Svo 

Mahan — Descriptive Geometry and Stone-cutting Svo 

Industrial Drawing. (Thompson.) Svo 

Mover — Descriptive Geometry Svo 

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Reid — Mechanical Drawing. (Elementary and Advanced.) Svo 

Text-book of Mechanical Drawing and Elementary Machine Design. Svo 

Robinson — Principles of Mechanism Svo 

Schwamb and Merrill — Elements of Mechanism Svo 

Smith (A. W.) and Marx — Machine Design Svo 

(R. S.) — Manual of Topographical Drawing. (McMillan.) Svo 

TiTSWORTH — Elements of Mechanical Drawing Oblong large Svo 

W.\RREN — Elements of Descriptive Geometry, Shadows, and Perspective. Svo 

Elements of Machine Construction and Drawing Svo 

Elements of Plane and Solid Free-hand Geometrical Drawing.. . . 12mo 

General Problems of Shades and Shadows Svo 

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Shadows 1 2mo 

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Plane Problems in Elementary Geometry 12mo 

Weisbach — Kinematics and Power of Transmission. (Herrmann and 

Klein.) Svo 

Wilson (H. M.) — Topographic, Trigonometric and Geodetic Surveying. Svo 

(V. T.) Descriptive Geometry Svo 

Free-hand Lettering Svo 

Free-hand Perspective " Svo 

WooLF — Elementary Course in Descriptive Geometry •. .Large Svo 



ELECTRICITY AND PHYSICS. 



Abegg — Theory of Electrolytic Dissociation, (von Ende.) 12mo, *1 25 

Andrews — Hand-book for Street Railway Engineers 3 X5 inches, mor., 1 25 

Anthony and Ball — Lecture-notes on the Theory of Electrical Measure- 
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and Brackett — Text-book of Physics. (Magie.) Small Svo, 3 00 

Benjamin — History of Electricity Svo, 3 00 

Betts — Lead Refining and Electrolysis Svo, 4 00 

Burgess and Le Chatelier — Measurement of High Temperatures. Third 

Edition Svo, *4 00 

Classen — Quantitative Analysis by Electrolysis. (Hall.) {In Press.) 

10 



Coi.Lixs — Manual of Wireless Telegraphy and Telephony 12mo,*Sl 50 

Crehore and Squier — Polarizing Photo-chronograph Svo, 3 00 

Danneel — Electrochemistry. (Merriam.) 12mo, *1 25 

Dawson — " Engineering " and Electric Traction Pocket-book. . 16mo, mor., 5 00 
DoLEZALEK — Theory of the Lead Accumulator (Storage Battery), (von 

Ende.) 12mo, 2 50 

DuHEivi — Thermodynamics and Chemistry. (Burgess.) Svo, 4 00 

Flather — Dynamometers, and the Measurement of Power 12mo, 3 00 

Getm.\n — Introduction to Physical Science 12mo, *1 50 

Gilbert — De Magnete. (Mottelay.) •. Svo, 2 50 

Hanchett — Alternating Currents 12mo, *1 00 

Hering — Ready Reference Tables (Conversion Factors) 16mo. mor., 2 .50 

Hobart and Ellis — High-speed Dynamo Electric Machinery Svo, *6 00 

HoLM.AK — Precision of Measurements Svo, 2 00 

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Hutchinson — High-Efficiency Electrical lUuminants and Illumination. 

Small Svo, *2 50 

Jones — Electric Ignition for Combustion Motors.' Svo. *4 00 

Karapetoff — Experimental Electrical Engineering: 

Vol. I Svo, *3 50 

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Kinzbrunner — Testing of Continuous-current Machines Svo, 2 00 

Koch — Mathematics of Applied Electricity Small Svo, *3 00 

Landauer — Spectrum Analysis. (Tingle.) Svo, 3 00 

Lauffer — Electrical Injuries 16mo, *0 50 

Lob — Electrochemistry of Organic Compounds. (Lorenz.) Svo, 3 00 

Lyndon — Development and Electrical Distribution of Water Power.. . .Svo, *3 00 

Lyons — Treatise on Electromagnetic Phenomena. Vols. I and II, Svo, each, *6 00 

Martin — Measurement of Induction Shocks 12mo, *1 25 

MicniE — Elements of Wave Motion Relating to Sound and Light Svo, *4 00 

Morgan — Physical Chemistry for Electrical Engineers 12mo, *1 50 

NoRRis — Introduction to the Study of Electrical Engineering Svo, *2 50 

Parshall and Hobart — Electric Machine Design 4to. half mor., *12 50 

ReaGjVN — Locomotives: Simple, Compound, and Electric Small Svo, 3 50 

RODENHAUSER and Schoenawa — Electric Furnaces in the Iron and Steel 

Industry (VoM Baur.) (/" Press.) 

Rosenberg — Electrical Engineering. (Haldanf. Gee — Kinzbrunner.) .Svo, *2 00 
Ry.\n — Design of Electrical Machinery: 

Vol. I. Direct Current Dynamos Svo, 

Vol. II. Alternating Current Transformers Svo, 

Vol. III. Alternators, Synchronous Motors, and Rotary Converters. 

Svo, 
Schapper — Laboratory Guide for Students in Physical Chemistry. . . . 12mo, 

TlLLM.\N — Elementary Lessons in Heat Svo, 

Timbie — Answers to Problems in Elements of Electricity 12mo, Paper, 

Elements of Electricity Small Svo, *2 00 

Essentials of Electricity 12mo, *1 25 

Tory and Pitcher — Manual of Laboratory Physics Small Svo, 2 00 

Ulke — Modern Electrolytic Copper Refining Svo, 3 00 

Waters — Commercial Dynamo Design Svo, *2 GO 



LAW. 

Brennan — Hand-book of Useful Legal Information for Business Men. 

lOmo, mor., *5 00 

Davis — Elements of Law Svo, *2 50 

Treatise on the Military Law of United States Svo, *7 00 

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Manual for Courts Martial lOmo, mor., 1 50 

Wait — Engineering and Architectural Jurisprudence Svo, 6 00 

Sheep, 50 

Law of Contracts Svo, 3 00 

Law of Operations Preliminary to Construction in Engineering and 

Architecture Svo, o 00 

Sheep, 5 50 

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MATHEMATICS. 

Baker— Elliptic Functions Svo, $1 50 

Briggs — Elements of Plane Analytic Geometry. (BocnER.) 12mo, 1 00 

Buchanan — Plane and Spherical Trigonometry 8vo, *1 00 

Byerly — Harmonic Functions 8vo, 1 00 

Chandler — Elements of the Infinitesimal Calculus 12mo, 2 00 

Coffin — Vector Analysis 12mo, *2 50 

CoMPTON — Manual of Logarithmic Computations » . 12mo, 1 50 

Dickson — College Algebra Small 8vo, *1 50 

Introduction to the Theory of Algebraic Equations Small 8vo, *1 25 

Emch — Introduction to Projective Geometry and its Application 8vo, 2 50 

FiSKE — Functions of a Complex Variable .8vo, 1 00 

Halsted — Elementary Synthetic Geometry 8vo, 1 50 

Elements of Geometry 8vo, 1 75 

Rational Geometry 12mo, *1 50 

Synthetic Projective Geometry Svo, 1 00 

Hancock — Lectures on the Theory of Elliptic Functions Svo, *5 00 

Hyde — Grassmann's Space Analysis Svo, 1 QO 

Johnson (J. B.) Three-place Logarithmic Tables: Vest-pocket size, paper, *0 15 

100 copies, *5 00 
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Curve Tracing in Cartesian Co-ordinates 12mo, 1 00 

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Elementary Treatise on Differential Calculus Small Svo, 1 50 

Elementary Treatise on the Integial Calculus Small Svo, 1 50 

Theoretical Mechanics 12mo, *3 00 

Theory of Errors and the Method of Least Squares 12mo, 1 50 

Treatise on Differential Calculus Small Svo, 3 00 

Treatise on the Integral Calculus Small Svo, 3 00 

Treatise on Ordinary and Partial Differential Equations. . . .Small Svo, 3 50 
Karapetoff — Engineering Applications of Higher Mathematics: 

Part I. Problems on Machine Design Small Svo, *0 75 

Koch — Mathematics of Applied Electricity Small Svo, *3 00 

Laplace — Philosophical Essay on Probabilities. (Truscott and Emory.) 

12mo, 2 00 
Le Messurier — Key to Professor W. W. Johnson's Differential Equations. 

Small Svo, *1 75 

Ludlow — Logarithmic and Trigonometric Tables Svo, *1 00 

and Bass — Elements of Trigonometry and Logarithmic and Other 

Tables Svo, *3 00 

Trigonometry and Tables published separately Each,' *2 00 

Macfarlane — Vector Analysis and Quaternions Svo, 1 00 

McMahon — Hyperbolic Functions Svo, 1 00 

MANNiNG-^Irrational Numbers and their Representation by Sequences and 

Series 12mo, 1 25 

Marsh — Industrial Mathematics Small Svo, *2 00 

Mathematical Monographs. Edited by Mansfield Merriman and 

Robert S. Woodward Octavo, each, 1 00 

No. 1. History of Modern Mathematics, by David Eugene Smith. 

No. 2. Synthetic Projective Geometry, by George Bruce Halsted. 

No. 3. Determinants, by Laenas Gifford Weld. 

No. 4. Hyperbolic Functions, by James McMahon. 

No. 5. Harmonic Functions, by William E. Byerly. 

No. 6. Grassmann's Space Analysis, by Edward W. Hyde. 

No. 7. Probability and Theory of Errors, by Robert S. Woodward. 

No. 8. Vector Analysis and Quaternions, by Alexander Macfarlane. 

No. 9. Differential Equations, by William Woolsey Johnson. 

No. 10. The Solution of Equations, by Mansfield Merriman. 

No. 11. Functions of a Complex Variable, by Thomas S. Fiske. 

M aurer — Technical Mechanics Svo, 4 00 

Merriman — Method of Least Squares Svo, 2 00 

Solution of Equations Svo, 1 00 

.MoRiTZ — Elements of Plane Trigonometry Svo, *2 00 

High School Edition Small Svo, *1 00 

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Rice and Johnson — Differential and Integral Calculus. 2 vols, in one. 

Small Svo, SI 50 

Elementary Treatise on the Differential Calculus Small Svo, 3 00 

Smith — History of Modern Mathematics Svo, 1 00 

Veblen and Lennes — Introduction to the Real Infinestimal Analysis of One 

Variable Svo, *2 00 

Waterbury — Vest Pocket Hand-book of Mathematics for Engineers. 

2| X5| inches, mor., *1 GO 

Enlarged Edition, Including Tables mor., *1 .50 

Weld — Determinants Svo, 1 00 

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Woodward — Probability and Theory of Errors Svo, 1 00 



MECHANICAL ENGINEERING. 

MATERIALS OF ENGINEERING, STEAM-ENGINES AND BOILERS. 

Bacon — Forge Practice 12mo, 1 50 

Baldwin — Steam Heating for Buildings 12mo, 2 50 

Barr and Wood — Kinematics of Machinery , . Svo, 2 50 

Bartlett — Mechanical Drawing. Third Edition Svo, .3 00 

Abridgment of the Second Edition.. . .Svo, *1 50 

Burr — Ancient and Modern Engineering and the Isthmian Canal Svo, *3 50 

Carpenter — Heating and Ventilating Buildings Svo, 

and Diederichs — Experimental Engineering Svo, 

Clerk — The Gas, Petrol and Oil Engine Svo, 

CoMPTON — First Lessons in Metal Working 12mo, 

and De Groodt — Speed Lathe 12mo, 

Coolidge — Manual of Drawing •. . . . Svo, paper, 

and Freeman — Elements of General Drafting for Mechanical Engi- 
neers Oblong 4to, 

Cromwell — Treatise on Belts and Pulleys 12mo, 

Treatise on Toothed Gearing 1 2mo, 

Dingey — Machinery Pattern Making V2mo, 

Durley — Kinematics of Machines Svo, 

Flanders — Gear-cutting Machinery Small Svo, 

Flather — Dynamometers and the Measurement of Power 12mo, 

Rope Driving 12mo, 

Fuller and Johnston — Applied Mechanics: 

Vol. I. Theory of Statics and Kinetics (In Press.) 

Vol. II. Strength of Materials (Iji Preparation.) 

Gill — Gas and Fuel Analysis for Engineers 12mo, 1 2.5 

Goss — Locomotive Sparks Svo, 2 00 

Greene — Elements of Heating and Ventilation Svo, *2 50 

Pumping Machinery Svo, *4 00 

Hering — P.eady Reference Tables (Conversion Factors) 16mo, mor., 2 .50 

Hobart and Ellis — High Speed Dynamo Electric Machinery Svo, *6 00 

Hutton — Gas Engine Svo. 

J.A.MISON — Advanced Mechanical Drawing Svo, 

Elements of Mechanical Drawing Svo, 

Jones — Gas Engine Svo, 

Machine Design: 

Part I. Kinematics of Machinery Svo, 

Part II. Form, Strength, and Proportions of Parts Svo, 

Kaup — Machine Shop Practice Small Svo, 

Kent — Mechanical Engineers' Pocket-Book IGmo, mor., 

Kerr — Power and Power Transmission Svo, 

KiMB..\LL and Barr — Machine Design Svo, 

King — Elements of the Mechanics of Materials and of Power of Trans- 
mission Svo, *2 50 

Lanza — Dynamics of Machinery Svo, *2 50 

Leonard — Machine Shop Tools and Methods Svo, 4 00 

Levin — Modern Gas Bugine and the Gas Producer Svo, *4 00 

Lorenz — Modern Refrigerating Machinery. (Pope, H.wen, and Dean.) 

Svo, *4 00 
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MAcCaRD — Kinematics; or, Practical Mechanism 8vo, $5 00 

Mechanical Drawing 4to, 4 00 

' Velocity Diagrams 8vo, 1 50 

MacFarland — Standard Reduction Factors for Gases 8vo, lj^50 

Mahan — Industrial Drawing. (Thompson.) Svo, 3 50 

Mehrtens — Gas Engine Theory and Design Small Svo, 2 50 

Oberg — Handbook of Small Tools Small Svo, 2 50 

Parshall and Hobart — Electric Machine Design. . .Small 4to, half leather, *12 50 
Peele — Compressed Air Plant. Second Edition, Revised and Enlarged. Svo, *3 50 

Poole — Calorific Power of Fuels Svo, 3 00 

Porter — Engineering Reminiscences, 1S55 to 1SS2 Svo, *3 00 

Reid — Mechanical Drawing. (Elementary and Advanced.) Svo, *2 00 

Text-book of Mechanical Drawing and Elementary Machine Design . Svo, 3 00 

Richards — Compressed Air 12mo, 1 50 

Robinson — Principles of Mechanism Svo, 3 00 

ScHWAMB and Merrill — Elements of Mechanism Svo, [ 3 00 

Smith (O.) — Press-working of Metals Svo, 3 00 

(A. W.) and Marx — Machine Design Svo, 3 00 

Sorel — Carbureting and Combustion in Alcohol Engines. (Woodward and 

Preston.) Small Svo, 3 00 

Stone — Practical Testing of Gas and Gas Meters Svo, 3 50 

Thurston — Animal as a Machine and Prime Motor, and the Laws of 

Energetics 12mo, 1 00 

Treatise on Friction and Lost Work in Machinery and Mill Work, .Svo, 3 00 

Tillson — Complete Automobile Instructor Kimo, *1 50 

Titsworth — Elements of Mechanical Drawing Oblong Svo, *1 25 

Warren — Elements of Machine Construction and Drawing Svo, 7 50 

Waterbury — Vest Pocket Hand-book of Mathematics for Engineers. 

2| X5i inches, mor., *1 00 

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Klein.) Svo, 5 00 

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MATERIALS OF ENGINEERING. 

Bottler — German and American Varnish Making. (Sabin.) . . .Small Svo, *3 50 

Burr — Elasticity and Resistance of the Materials of Engineering Svo, 7 50 

Church — Mechanics of Engineering Svo, 6 00 

Mechanics of Solids (Being Parts I, II, III of Mechanics of Engineering). 

Svo, 4 50 
Fuller and Johnston — Applied Mechanics: 

Vol. I. Theory of Statics and Kinetics {In Press.) 

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Greene — Structural Mechanics Svo, *2 50 

HoLLEY — Analysis of Paint and Varnish Products Small Svo, *2 50 

Lead and Zinc Pigments Small Svo, *3 00 

Johnson (C. M.) — Rapid Methods for the Chemical Analysis of Special 

Steels, Steel-making Alloys and Graphite Small Svo, 3 00 

(J. B.) Materials of Construction Svo, 6 00 

Keep— Cast Iron Svo, 2 50 

King — Elements of the Mechanics of Materials and of Power of Trans- 
mission Svo, *2 50 

Lanza — Applied Mechanics Svo, 7 50 

Lowe — Paints for Steel Structures 12mo, 1 00 

Maire — Modern Pigments and their Vehicles 12mo, 2 00 

Martin — Text-Book of Mechanics: 

Vol. I. Statics 12mo, *1 25 

Vol. II. Kinematics and Kinetics 12mo, *1 50 

Vol. III. Mechanics of Materials 12mo, *1 50 

Vol. IV. Applied Statics 12mo, *1 50 

Maurer — Technical Mechanics Svo, 4 00 

Merriman — Mechanics of Materials Svo, 5 00 

Strength of Materials 12mo, *1 00 

Metcalf — Steel. A Manual for Steel-users 12mo, 2 00 

MuRDOCK — Strength of Materials 12mo, *2 00 

14 



Sarin — Industrial and Artistic Technology of Paint and Varnish 8vo, 

Smith (A. W.) — Materials of Machines 12mo, 

(H. E.) — Strength of Materia! 12mo, 

Thurston — Materials of Engineering 3 vols., 8vo, 

. Part I. Non-metallic Materials of Engineering 8vo, 

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Constituents Svo, 

Waterbury — Laboratory Manual for Testing Materials of Construction. 

12mo, 

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vation of Timber Svo, 

(M. P.) Rustless Coatings. Corrosion and Electrolysis of Iron and 
Steel Svo, 



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STEAM-ENGIXES AND BOILERS. 



Abrah.\m — Steam Economy in the Sugar Factory. (Bayle.) . . . {In Press.) 
Berry — Temperature-entropy Diagram. Third Edition Revised and En- 
larged I 12mo 

C.^RNOT — Reflections on the Motive Power of Heat. (Thurston.). . . 12mo 

Chase — Art of Pattern Making 12mo 

Creighton — Steam-engine and other Heat Motors Svo 

Dawson — " Engineering " and Electric Traction Pocket-book. ..16mo, mor. 

Gebhardt — Steam Power Plant Engineering Svo 

Goss — Locomotive Performance Svo 

Hemenway — Indicator Practice and Steam-engine Economy 12mo 

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King — Steam Engineering {In Preis.) 

Kneass — Practice and Theory of the Injector Svo 

MacCord — Slide-valves Svo 

Meyer — Modern Locomotive Construction 4to 

Miller, Berry, and Riley — Problems in Thermodynamics.. . .Svo, paper, 

Moyer — Steam Turbines Svo 

Peabody — Manual of the Steam-engine Indicator 12mo 

Tables of the Properties of Steam and Other Vapors and Temperature- 
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Valve-gears for Steam-engines Svo 

and Miller — Steam-boilers Svo 

Perkins — Introduction to General Thermodynamics 12mo 

Pupin — Thermodynamics of Reversible Cycles in Gases and Saturated 

Vapors. (Osterberg.) 12mo 

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Small Svo 

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Smart — Handbook of Engineering Laboratory Practice 12mo 

Snow — Steam-boiler Practice Svo 

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Valve-gears Svo 

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THOM.A.S — Steam-turbines Svo 

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Operation Svo 

Manual of the Steam-engine 2 vols., Svo 

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Wehrenfennig — Analysis and Softening of Boiler Feed-water. (Patter- 
son.) Svo 

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WHITH.A.M — Steam-engine Design Svo 

Wood — Thermodynamics, Heat Motors, and Refrigerating Machines. . .8vo 

15 



2 50 

1 50 

2 50 
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1 50 

2 00 
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MECHANICS PURE AND APPLIED. 

Church- — Mechanics of Engineering .... Svo, S6 00 

Mechanics of Solids (Being Parts I, 11, III of Mechanics of Engineering). 

Svo, 
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Mechanics of Internal Work Svo, 

Notes and Examples in Mechanics Svo, 

Dana — Text-book of Elementary Mechanics for Colleges and Schools.. 12mo, 
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Vol. I. Kinematics Svo, 

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Mechanics of Engineering. Vol. I Small 4to, 

Vol. II Small 4to, 10 00 

Fuller and Johnston — Applied Mechanics: 

Vol. I. Theory of Statics and Kinetics {In Press.) 

Vol. II. Strength of Materials {In Preparaiion.) 

Greene — Structural Mechanics Svo, *2 50 

Hartmanx — Elementary Mechanics for Engineering Stitdents 12mo, *1 25 

James — Kinematics of a Point and the Rational Mechanics of i Particle. 

. Small Svo, 2 00 

Johnson (W. W.) Theoretical Mechanics 12mo, *3 00 

King — Elements of the Mechanics of Materials and of Power of Trans- 
mission Svo, *2 50 

KoTTCAMP — Exercises for the Applied Mechanics Laboratory, Loose Leaf 

Laboratory Manual Oblong 4to, paper, *1 00 

Lanza — Applied Mechanics Svo, 7 50 

Martin — Text Book of Mechanics: 

Vol. I. Statics 12mo, *1 25 

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Vol. III. Mechanics of Materials 12mo, *1 50 

Vol. IV. Applied Statics 12mo, *1 .50 

Maurer — Technical Mechanics Svo, 4 00 

Merri.m.\n — Elements of Mechanics 12mo, *1 00 

Mechanics of Materials Svo, 5 00 

MiCHlE — Elements of Ana'vtical Mechanics Svo, *4 00 

Robinson — Principles of Mechanism Svo, 3 00 

Sanborn — Mechanics Problems. Small Svo, *1 50 

ScHVVAMB and Merrill — Elements of Mechanism Svo, 3 00 

Wood — Elements of Analytical Mechanics Svo, 3 00 

Principles of Elementary Mechanics 12mo, 1 25 

MEDICAL. 

Abderhalden — Physiological Chemistry in Thirty Lectures. (H.all and 

Defren.) Svo, *5 00 

von Behring — Suppression of Tuberculosis. (Bolduan.) 12mo, 1 00 

BoLDU.\N — Immune Sera 12mo, *1 50 

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Chapin — The Sources and Modes of Infection Small Svo, *3 00 

CoHNHElM — Enzymes 12mo, * 1 50 

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Fischer — Nephritis Small Svo, *2 50 

Oedema Svo, *2 00 

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Fuller — Qualitative Analysis of Medicinal Preparations 12mo, *1 50 

Hammarsten — Text-book on Physiological Chemistry. (Mandel.).. . .Svo, *4 00 
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Lassar-Cohn — Praxis of Urinary Analysis. (Lorenz.) 12mo, 1 00 

Lauffer — Electrical Injuries 16mo, *0 .50 

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IG 



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RUDDIMAN — Incompatibilities in Prescriptions 8vo, 2 00 

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Salkowski — Physiological and Pathological Chemistry. (Orndorff.) . 8vo, 2 50 

Satterlee — Outlines of Human Embryology 12mo, *1 25 

Smith — Lecture Notes on Chemistry for Dental Students Svo, *2 50 

Whipple — Typhoid Fever Small Svo, *3 00 

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Betts — Lead Refining by Electrolysis Svo, 4 00 

Holland — Encyclopedia of Founding and Dictionary of Foundry Terms 

used in the Practice of Moulding 12mo, 3 00 

Iron Founder 12mo, 2 50 

BoRCHERS — Metallurgy. (Hall and Havward.) Svo, *3 00 

Burgess and Le Chateliek — Measurement of High Temperatures. Third 

Edition Svo, *4''00 

Douglas — Untechnical Addresses on Technical Subjects 12mo, 1 00 

GoESEL — Minerals and_Metals: A Reference Book 16mo, mor., 3 00 

Iles — Lead-smelting 12mo, *2 50 

Johnson — Rapid Methods for the Chemical Analysis of Special Steels, 

Steel-making Alloys and Graphite Large, 12mo, 3 00 

Keep — Cast Iron 8vo, 2 .50 

Metcalf — Steel. A Manual for Steel-users 12mo, 2 00 

MiNET — Production of Aluminum and its Industrial Use. (Waldo.).. 12mo, 2 50 

Palmer — Foundry Practice Small Svo, *2 00 

Price and Meade — Technical Analysis of Brass 12mo, *2 00 

Rodenhauser and Schoenawa — Electric Furnaces in the Iron and Steel 

Industry. (VoM Baur.) (i« Press ) ' ' 

RuER — Elements of Metallography. (Mathewson.) Svo, *3 00 

Smith — Materials of Machines 12mo, 1 00 

Tate and Stone — Foundry Practice 12mo, 2 00 

Thurston — Materials of Engineering. In Three Parts Svo, S 00 

Part I. Non-metallic Materials of Engineering, see Civil Engineering, 

page 9. 

Part II. Iron and Steel 8vo, 3 50 

Part III. A Treatise on Brasses, Bronzes, and Other Alloys and Their 

Constituents Svo, 2 ,50 

Ulke — Modern Electrolytic Copper Refining 8vo, 3 00 

West — American Foundry Practice 12mo. 2 .50 

Moulders' Te.xt Book 12mo, 2 50 

MILITARY AND MARINE ENGINEERING. 

ARMY AND NAVY. 

Bernadou — Smokeless Powder, Nitro-cellulose, and the Theory of the Cellu- 
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Chase— Art of Pattern Making 12mo, 2 50 

Screw Propellers and Marine Propulsion Svo, 3 00 

Cloke — Enlisted Specialists' Examiner Svo, *2 00 

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Craig — Azimuth 4to, 3 50 

Crehore and Squier — Polarizing Photo-chronograph Svo, 3 00 

Davis — Elements of Law Svo, *2 50 

Treatise on the Military Law of United States 8vo *7 00 

17 



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DuRAND — Resistance and Propulsion of Ships 8vo, 5 00 

Dyer— Handbook of Light Artillery 12mo, *3 00 

EissLER — Modern High Explosives 8vo, 4 00 

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Hamilton and Bond— The Gunner's Catechism 18mo, 1 00 

HoFF — Elementary Naval Tactics 8vo, *1 50 

Ingalls — Handbook of Problems in Direct Fire 8vo, 4 00 

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Lissak — Ordnance and Gunnery 8vo, *6 00 

Ludlow — Logarithmic and Trigonometric Tables 8vo, *1 00 

Lyons — Treatise on Electromagnetic Phenomena. Vols. I. and IL, 8vo. each, *6 00 

Mahan — Permanent Fortifications. (Mercur) 8vo, half mor., *7 50 

Manual for Courts-martl-^l IGmo, mor., 1 50 

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Elements of the Art of War 8vo, *4 00 

Nixon — -Adjutants' Manual 24mo, 1 00 

Peabody — N aval Architecture 8vo, 7 50 

Propellers 8vo, 1 25 

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Rust — Ex-meridian Altitude, Azimuth and Star-Finding Tables 8vo, 5 00 

Selkirk — Catechism of Manual of Guard Duty 24mo, *0 50 

Sharpe — Art of Subsisting Armies in War 18mo, mor., 1 50 

Taylor — Speed and Power of Ships. 2 vols. Text 8vo, plates oblong 4to, *7 50 
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Woodhull — Military Hygiene for Officers of the Line Small 8vo, *1 50 



MINERALOGY. 

Browning — Introduction to Rarer Elements Svo, *1 50 

Brush — Manual of Determinative Mineralogy. (Penfield.) 8vo, 4 00 

Butler — Pocket Hand-book of Blowpipe Analysis lOmo, '*0 75 

Pocket Hand-book of Minerals. 16mo, mor., 

Chester — Catalogue of Minerals Svo, paper. 

Cloth, 

Crane — Gold and Silver Svo, 

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Manual of Mineralogy. (Ford.) 12mo, 

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Eakle — Mineral Tables Svo, 

Eckel — Building Stones and Clays ". Svo, *3 00 

Goesel — Minerals and Metals: A Reference Book 16mo, mor., 3 00 

Groth — The Optical Properties of Crystals. (Jackson.) Svo, *3 50 

Introduction to Chemical Crystallography. (Marshall.) 12mo, 1 25 

Hayes — Handbook for Field Geologists IGmo, mor., 

Iddings — Igneous Rocks Svo, 

Rock Minerals 8vo, 

JoHANNSEN — Determination of Rock-forming Minerals in Thin Sections, Svo, 

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Lewis — Determinative Mineralogy Small Svo, 

Martin — Laboratory Guide to Qualitative Analysis with the Blowpipe. 12mo, *0 GO 

Merrill — Non-metallic Minerals: Their Occurrence and Uses Svo, 4 00 

Stones for Building and Decoration Svo, 5 00 

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Pirsson — Rocks and Rock Minerals 12mo, *2 50 

Richards — Synopsis of Mineral Characters 12mo, mor., *1 25 

18 



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RiES — Building Stones and Clay Products 8vo,*S3 00 

Clays: Their Occurrence, Properties and Uses 8vo, *5 GO 

and Leighton — History of the Clay-working Industry of the United 

States 8vo, *2 50 

RowE — Practical Mineralogy Simplified 12mo, *1 25 

Tillman — Text-book of Important Minerals and Rocks 8vo, *2 00 

Washington — Manual of the Chemical Analysis of Rocks 8vo, 2 GO 



MINING. 

Beard — Mine Gases and Explosions Small Svo, *3 00 

Brunswig — Explosives. (Munroe and Kibler.) Ready Fall, 1912 

Crane— Gold and Silver Svo, *5 00 

Index of Mining Engineering Literature, Vol. I Svo, *4 00 

Svo, mor., *5 00 

Vol. II Svo, *3 00 

Svo, mor., *4 00 

Ore Mining Methods Svo, *3 00 

Dana and Saunders — Rock Drilling Svo, *4 00 

Douglas — Untechnical Addresses on Technical Subjects 12mo, 1 00 

Eissler — Modern High Explosives Svo, 4 00 

Gilbert, Wightman and Saunders — Subways and Tunnels of New York. ■ 

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Goesel — Minerals and Metals: A Reference Book 16mo, mor., 3 00 

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Iles — Lead Smelting l2mo, *2 50 

Peele — Compressed Air Plant Svo, *3 50 

RiEMER — Shaft Sinking under Difficult Conditions. (Corning and Peele.) 

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Weaver — Military Explosives Svo, *3 00 

Wilson — Hydraulic and Placer Mining 12mo, 2 50 

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Association of State and National Food and Dairy Departments, 

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Bashore — Outlines of Practical Sanitation 12mo, *1 25 

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Folvvell — Sewerage. (Designing, Construction, and Maintenance.). .. Svo, 3 00 

Water-supply Engineering Svo, 4 00 

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Fuertes — Water-filtration Works 12mo, 2 50 

Gerhard — Guide to Sanitary Inspections 12mo, 1 50 

Modern Baths and Bath Houses Svo, *3 00 

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The Water Supply, Sewerage, and Plumbing of Modern City Buildings. 

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Filtration of Public Water-supplies Svo, 3 00 

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Leach — Inspection and Analysis of Food with Special Reference to State 

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Mason — Examination of Water. (Chemical and Bacteriological.). ... 12mo, 1 25 

Water-supply. (Considered principally from a Sanitary Standpoint.) 

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Merriman — Elements of Sanitary Engineering Svo, *2 00 

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Ogden and Cleveland — Practical Methods of Sewage Disposal for Res- 
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Parsons — Disposal of Municipal Refuse Svo 2 00 

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Richards — Conservation by Sanitation 8vo, 2 50 

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